IS.  DEPARTMENT   QF   AGRICULTURE, 

OFFICE  OF  EXPERIMENT  STATIONS    BULLETIN  NO.  126. 


A.  C.  TRUE,   Di 


STUDIES  OX  THE  DIGESTIBILITY  AM) 
NUTRITIVE  VALUE  OF  BREAD 


THE  UNIVERSITY  OF  MINNESOTA 


IX 


.      D^CUVM?NT^iS»T. 

.13 

o< 

U.S.  DEPOSITORY 

OO-10O2. 


HARRY  SNYDER,  B.  S., 

Professor  of  Chemistry,  College  qf  Agriculture,  University  0/ Minnesota,  ami 
Chemist,  Agricultural  Experiment  Station. 


WASHINGTON: 

GOVERN M  E XT  PRINTING  OFFICE 

1  9  0  3 . 


LIST  OF  PUBLICATIONS  OF  THE  OFFICE  OF  EXPERIMENT  STATIONS  ON 
THE  FOOD  AND  NUTRITION  OF  MAN. 

\<>i  e.— For  those  publications  to  which  a  price  is  affixed  application  should  be  made  to  the  Super- 
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♦Charts.    PpOd    and    Diet.       By   W.   <  >.    Atwater.      i  Four    charts,    20    by   4U    inches.)       Price    per   set, 

unmounted,  75  cents. 
*Bul.  21.   Methods  and  Results  of  investigations  on  the  Chemistry  and  Economy  of  Food.    ByW.O. 

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Bui.  2-s.    i  Revised   edition,  i     The   Chemical    Composition   of   American    Food    Materials.     ByW.O, 

Atwater  and  A.  P.  Bryant.     Pp. ST.     Price,  5  cents. 
Bui.  29.    Dietary  Studies  at  the  University  of  Tennessee  in  1895.     By  C.  E.  Wait,  with  comments  by 

W. O.  Atwater  and  C.  I>.  Woods.     Pp. 45.     Price.  f>  cents. 
Bid.  31.    Dietary  Studies  at  the  University  of  Missouri  in  1895,  and  Data  Relating  to  Bread  and  Meat 

Consumption  in  Missouri.     By  II.  B.  Cibson,  S.Calvert,  and  D.W.May,  with  comments  by 

W.O.  Atwater  and  C.D.Woods.     Pp.24.     Price.  5  cents. 
*Bul.  32.   Dietary  Studies  at  Purdue  University,  Lafayette,  Ind.,  in  1895.     By  W.  K.  Stone,  with  com- 
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Bui.  35.    Food  and  Nutrition  Investigations  in  New  Jersey  in  1895  and  1896.  By  E.  B.  Voorhees.  Pp.  4u. 

Price,  5  cents. 
Bid.  37.   Dietary  Studies  at  the  Maine  State  College  in  1895.     By  W.  H.Jordan.    Pp.57.    Price,  5  cents. 
Bui.  38.    Dietary  Studies  with  Reference  to  the  Food  of  the  Negro  in  Alabama  in  1895  and  1896.     Con- 
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Bui.  44.  Report  of  Preliminary  Investigations  on  the  Metabolism  of  Nitrogen  and  Carbon  in  the 

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Atwater,  CD.  Woods,  and  F.  G.  Benedict.     Pp.  64.    Price,  5  cents. 
Bui.  45.  A  Digest  of  Metabolism  Experiments  in  which  the  Balance  of  Income  and  Outgo  was 

Determined.    By  W.  O.  Atwater  and  C.   F.  Langworthy.     Pp.  434.     Price,  25  cents. 
Bui.  46.  Dietary  Studies  in  New  York  City  in  1895  and  1896.    By  W.  O.  Atwater  and  C  D.  Wood-. 

Pp.117.    Price,  10  cents. 
Bui.  52.   Nutrition    Investigations  in  Pittsburg,  Pa.,    1894-1896.    By  Isabel  Bevier.     Pp.  48.     Price, 

5  cents. 
Bui.  53.   Nutrition  Investigations  at  the  University  of  Tennessee  in  18%  and  1897.     By  c.  E.  Wait. 

Pp.  46.    Price,  5  cents. 
Bui.  54.   Nutrition  Investigations  in  New  Mexico  in  1897.   ByA.Goss.    Pp   20.     Price,  5  cents. 
Bui.  55.   Dietary  Studies  in  Chicago  in   1895  and   1896.     Conducted  with  the  cooperation  of  Jane 

Addams  and  Caroline  L.  Hunt,  of  Hull  House.    Reported  by  W.  O.  Atwater  and  A.  P. 

Bryant.    Pp.76.    Price,  5  cents. 
*  Bui.  56.   History  and  Present  Status  of  Instruction  in  Cooking  in  the  Public  Schools  of  New  York 

City.     Reported  by  Mrs.    Louise  E.  Hogan,  Avith  an    introduction  by  A.  C.  True.  Ph.D. 

Pp.  70.    Price,  5  cents. 
Bui  t«.   Description  of  a  New  Respiration  Calorimeter  and  Experiments  on  the  Conservation  of  Energy 

in  the  Human  Body.     ByW.O.  Atwater  and  E.  B.  Rosa.     Pp.94.     Price,  10  cents. 
Bui.  tit'..  The  Physiological  Effect  of  Creatin  and  Creatinin  and  their  Value  as  Nutrients.    By  J.  W. 

Mallet.     Pp.24.     Price,  5  cents. 
Bui.  (i7.   Studies  on  Bread  and  Bread  Making.     By  Harry  Snyder  and  L.  A.  Voorhees.     Pp.  51.     Price, 

10  cents. 
Bui   68.    A  Description  of  Some  Chinese  Vegetable  Food  Materials  and  Their  Nutritive  and  Economic 

ValUe,     By  W.  C.  Blasdale.     Pp.   IS.     Price,  10  cents. 
Bui  69.    Experiments  on  the  Metabolism  of  Matter  and   Energy  in   the  Human   Body.     By  W.  o. 

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[Continued  on  third  page  of  cover.] 


U.  S.  DEPARTMENT   OF   AGRICULTURE. 

OFFICE  OF  EXPERIMENT  STATIONS    BULLETIN  NO.  126. 

A.  C.  TRUE,   Director. 


STUDIES  ON  THE  DIGESTIBILITY  AND 
NUTRITIVE  VALUE  OF  BREAD 


THE  UNIVERSITY  OF  MINNESOTA 


1900-190  2 


BY 


HARRY  SNYDER,  B.  S., 

Professor  of  Chemistry,  College  of  Agriculture,  Universit;/  of  Minnesota,  and 
Chemist,  Agricultural  Experiment  Station. 


WASHINGTON: 

GOVERNMENT     PRINTING     OFFICE 

1903. 


OFFICE  OF  EXPERIMENT  STATIONS. 

A.  C.  True,  Ph.  D.,  Director. 

E.  W.  Allen,  Ph.  D.,  Assistant  Director  and  Editor  of  Experiment  Station  Record. 
C.  F.  Langworthy,  Ph.  D.,  Editor  and  Expert  on  Foods  and  Animal  Production. 

NUTRITION    INVESTIGATIONS. 

W.  0.  Atwater,  Ph.  D.,  Chief  of  Nutrition  Investigations,  Middletown,  Conn. 
C.  D.  AVoods,  B.  S.,  Special  Agent  at  Orono,  Me. 

F.  G.  Benedict,  Ph.  D.,  Physiological  Che  mist,  Middletown,  ''arm. 
R.  D.  Milner,  Ph.  B.,  Editorial  Assistant,  Middletown,  Conn. 

2 


LETTER  OF  TRANSMITTAL 


r.  S.  Department  of  Agriculture, 
Office  of  Experiment  Stations, 

Washington,,  D.  C,  Fdruary  15,  1903. 
Sir:  I  have  the  honor  to  transmit  herewith,  and  to  recommend  for 
publication  as  a  bulletin  of  this  Office,  a  report  of  investigations  on 
tin4  digestibility  and  nutritive  value  of  bread  carried  on  at  the  Uni- 
versity of  Minnesota  in  1900-1902  by  Harry  Snyder,  professor  of 
chemistry  in  the  State  university  and  chemist  of  the  agricultural 
experiment  station.  The  studies  were  conducted  under  the  imme- 
diate supervision  of  Prof.  W.  O.  Atwater,  chief  of  nutrition  investi- 
gations, and  Prof.  Charles  D.  Woods,  and  form  a  part  of  the  investi- 
gations on  food  of  man  conducted  under  the  auspices  of  this  Office. 
Thanks  are  due  the  Northwestern  Consolidated  Milling  Company,  of 
Minneapolis,  Minn.,  for  specially  grinding  samples  of  hard  wheat, 
and  to  the  Goshen  Milling  Company,  of  Goshen,  Ind.,  and  the  Christian 
Breisch  Milling  Company,  of  North  Lansing,  Mich.,  for  similar  favors 
with  respect  to  soft  wheat. 

The  results  of  these  investigations  are  in  accord  with  those  obtained 
in  former  studies,  and  indicate  that  fine  patent  flours  from  both  hard 
and  soft  wheat  are  more  digestible  than  corresponding  coarse  flours, 
though  they  contain  somewhat  less  protein  and  mineral  matter  pound 
for  pound.  The  investigations  also  show  that  all  flours  are  quite 
thoroughly  digested,  and  furnish  experimental  proof  of  the  generalh' 
recognized  fact  that  wheat  flours  of  all  grades  are  among  the  most 
important  articles  of  diet. 

Respectfully,  A.  C.  True, 

Director. 
Hon.  James  Wilson. 

Secretary  of  Agriculture. 

3 


CONTENTS. 


Page. 

Introduction 7 

Methods  of  Bampling  and  analysis 8 

Description  of  samples  of  food  materials 10 

Composition  of  samples  of  food  materials 12 

Composition  of  feces  and  urine  obtained  in  digestion  experiments 17 

Experimental  methods 18 

Details  of  the  digestion  experiments  with  bread  from  different  grades  of  hard 

spring  wheat  flour 20 

Digestion  experiment  No.  242 21 

Digestion  experiment  No.  243 22 

Digestion  experiment  No.  244 23 

Digestion  experiment  No.  245 23 

Digestion  experiment  No.  246 24 

Digestion  experiment  No.  247 25 

Digestion  experiment  No.  248 26 

Digestion  experiment  No.  249 26 

Digestion  experiment  No.  250 27 

Summary  of  results  obtained  with  hard  spring  wheat  products 28 

Details  of  the  digestion  experiments  with  bread  from  different  grades  of  soft 

winter  wheat  flour 32 

Digestion  experiment  No.  309 32 

Digestion  experiment  No.  310 33 

Digestion  experiment  No.  311 34 

Digestion  experiment  No.  312 35 

Digestion  experiment  No.  313 35 

Digestion  experiment  No.  314 36 

Digestion  experiment  No.  315 37 

Digestion  experiment  No.  316 38 

Digestion  experiment  No.  317 38 

Digestion  experiment  No.  318 39 

Digestion  experiment  No.  319 40 

Digestion  experiment  No.  320 41 

Digestion  experiment  No.  321 41 

Digestion  experiment  No.  322 42 

Digestion  experiment  No.  323 43 

Summary  of  results  obtained  with  soft  winter  wheat  products. 44 

General  summary  of  results  and  conclusions 50 

5 


ILLUSTRATIONS. 


Page. 
Plate  I.  Fig.  1. — Flour  particles  from  straight  patent  floor  No.  240.     Fig.  2. — 

Flour  particles  in  >m  entire-wheat  rlour  No.  241 4S 

II.  P"ig.  1. — Flour  particles  from  graham  floor  No.  24.;.     Fig.  2.  —  1 

from  bread  fin  mi  straight  patent  rlour 48 

III.   Fig.  1. — Feces  from  bread  made  from  graham  flour.     Fig.  2. — Ft- 

from  bread  made  from  entire-wheat  rlour 48 

6 


STUDIES  ON  THE  DIGESTIBILITY  AND  NUTRITIVE 
VALUE  OF  BREAD. 


INTRODUCTION. 

The  investigations  reported  in  this  bulletin,  which  were  carried  on  at 
the  University  of  Minnesota  in  1900-1902,  are  a  continuation  of  the 
experiments  on  the  digestibility  and  comparative  nutritive  value  of 
bread  made  from  different  grades  of  flour  reported  in  previous  bulle- 
tins of  this  Office,0  and  include  two  series  of  digestion  and  nitrogen 
metabolism  experiments  with  healthy  men  on  a  diet  of  milk  and  bread 
made  from  different  grades  of  wheat  flour,  namely,  straight  patent, 
entire  wheat,  and  graham.  In  the  first  series,  which  included  9 
experiments  carried  on  in  1900-1901  (pp.  20-31),  the  different  grades  of 
flour  used  were  all  ground  from  the  same  lot  of  hard  Scotch  Fife  spring 
wheat.  In  the  second  series,  which  included  15  experiments,  carried 
on  in  1901-2  (pp.  32-50),  the  flours  were  ground  from  soft  winter  wheat. 

The  standard  grades  of  flour  produced  by  the  modern  process  of 
milling  are  discussed  in  detail  in  a  former  bulletin6  and  also  in  later 
pages  of  this  bulletin.  Briefly  stated,  by  graham  flour  is  meant  the 
product  obtained  by  grinding  the  entire  wheat  kernel.  Entire-wheat 
flour  is  the  product  obtained  by  removing  about  one-half  of  the  coarse 
bran  before  grinding.  This  flour  is  liner  than  graham,  but  not  as  tine 
as  the  patent  grades  of  flour.  In  milling  the  patent  flour  all  of  the 
bran  is  removed.  Several  grades  of  patent  flour  are  produced,  but 
the  one  most  commonly  found  on  the  market,  known  as  "  standard 
patent,'1  "straight  patent,"  or  "straight  grade"  consists  of  the  first 
and  second  patent  and  first  clear  grades  combined.  By  ordinary  proc- 
esses of  milling  a  little  over  72  per  cent  of  the  total  wheat  is  recovered 
as  straight  or  standard  patent  flour  and  about  2.5  per  cent  as  low  grade 
and  "red  dog"  flours,  the  remaining  2d  percent  being  returned  in  the 
form  of  bran,  shorts,  and  other  offal. 

During  late  years  the  relative  food  value  and  merits  of  these  differ- 
ent kinds  of  flour  have  been  the  subject  of  extensive  discussion;  but 
an  examination  of  the  literature  on  bread  and  flour  shows  that  but  few 
digestion  experiments  which  are  really  directly  comparable  have  been 

"V.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Buls.  67  and  101. 
H\  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Bui.  101,  pp.  7,8. 


8 

math4  with  the  different  kinds  of  flour.  Wheat  ranges  in  protein  con- 
tent from  about  11  to  IT  per  cent;  therefore,  in  order  that  the  results  of 
experiments  may  be  comparable,  the  three  kinds  of  flour  should  be 
milled  from  the  same  lot  of  wheat.  In  the  former  report  it  was  shown 
that  when  the  three  different  kinds  of  flour  were  ground  from  the  same 
lot  of  hard  spring  wheat  the  graham  and  entire-wheat  flours  contained 
a  little  more  protein  and  gave  a  slightly  higher  fuel  value  than  the 
straight  patent  flour;  but  the  coarser  graham  and  entire-wheat  flours 
had  a  lower  coefficient  of  digestibilit}r  than  the  liner  straight  patent 
flour.  Hence  the  straight  patent  flour  furnished  the  body  more 
nutritive  material  per  gram  or  per  pound  than  either  the  graham  or 
entire-wheat  flour.  Because  of  the  importance  of  the  subject  and  the 
extensive  use  of  wheat  as  a  human  food  it  was  deemed  desirable  to 
repeat  the  wTork,  and  in  so  doing  to  extend  the  periods  of  the  digestion 
experiments  over  a  longer  time  than  in  the  case  of  the  experiments 
previously  reported,  in  which  they  were  only  two  da\Ts  each.  The 
experiments  of  1900-1901  were  therefore  practically  a  repetition  of 
those  of  1899-1900,  except  that  the  digestion  period  in  each  case  was 
twice  as  long,  i.  e.,  four  days. 

In  1901-2  experiments  were  made  similar  to  those  of  1900-1901,  but 
with  soft  winter  wheat,  which  is  somewhat  different  in  character  from 
the  hard  spring  wheat,  in  order  to  determine  whether  the  results  would 
be  the  same  with  flours  ground  from  different  sorts  of  wheat. 

In  connection  with  both  series  of  experiments  a  number  of  analyses 
were  made  of  the  varieties  of  wheat  studied  and  of  their  milling  products 
as  well  as  of  the  milk  which  formed  a  part  of  the  diet  in  the  digestion 
experiments.  The  necessary  analyses  were  also  made  of  the  feces  and 
urine  to  secure  data  for  use  in  computing  the  .digestibility  of  the  food 
and  the  balance  of  income  and  outgo  of  nitrogen. 

METHODS  OF  SAMPLING  AND  ANALYSIS. 

The  analytical  methods  employed  in  these  investigations  were  prac- 
tically those  recommended  by  the  Association  of  Official  Agricultural 
Chemists/'  a  few  modifications  suggested  by  experience  being  intro- 
duced. 

A  sample  of  each  loaf  of  bread  used  during  the  separate  digestion 
experiments  was  analyzed.  One  hundred  grams  of  bread  was  reserved 
for  the  dry  matter  determination,  and  proportional  parts  of  the  dry 
matter  of  the  bread  from  various  loaves  were  united  to  form  a  com- 
posite sample,  which  contained  a  part  of  each  loaf  of  bread  propor- 
tioned to  the  size  and  moisture  content  of  the  loaf. 

A  composite  sample  was  made  of  the  milk  in  the  experiments  of 
1900-1901  by  saving,  in  a  bottle  containing  100  milligrams  of  potas- 

"  l".  S.  Dept.  Agr.,  Division  of  Chemistry  Bui.  46,  revised. 


shun  bichromate,  25  cubic  centimeters  of  the  mills  used  ut  each  meal. 
In  the  experiments  of  L901  2  the  amount  of  milk  reserved  at  each 
meal  was  50  cubic  centimeters.     The  temperature  of  the  drying  oven 

was  kept  at  about  60  C.  in  all  cases  of  the  determination  of  moisture 
in  the  feces.  The  bread  was  also  dried  at  this  temperature.  Nitrogen 
was  determined  by  the  ordinary  Kjeldahl  process.  In  the  case  of 
wheat  and  its  milling  products  and  bread,  protein  was  obtained  by 
multiplying  nitrogen  by  the  factor  5.7.  In  the  case  of  protein  in  the 
milk  and  the  (vers  the  factor  used  was  6.25.  No  attempt  was  made  to 
separate  and  determine  the  amount  of  metabolic  nitrogen  of  the  feces. 
Carefully  purified  ether  was  used  for  determining  ether  extract  in 
the  bread  and  feces.  The  results  obtained  for  the  fat  in  the  U^-^s 
were  not  satisfactory  in  many  cases,  although  the  determinations  were 
made  in  duplicate  by  the  method  generally  followed  and  considered 
reliable.  The  fat  in  the  milk  was  determined  by  the  Adams  gravi- 
metric method.  The  ash  was  determined  by  combustion  at  a  low  tem- 
perature. The  carbohyd rates  were  estimated  by  subtracting  the  sum 
of  the  protein,  ether  extract,  water,  and  ash  from  100. 

The  determination  of  the  ether  extract  in  the  feces  necessarily 
inyolyes  an  error,  owing  to  the  metabolic  products  present.  Another 
source  of  error  is  in  the  protein  determination.  While  the  determi- 
nation of  the  total  nitrogen  is  satisfactory,  the  factor  for  conyerting 
this  nitrogen  into  protein  is  not  perfectly  reliable,  and  in  many  cases 
is  very  unsatisfactory.  It  is  well  known  that  not  all  of  the  nitrogen 
of  a  food  is  in  the  form  of  proteid  compounds.  In  the  case  of  the 
food  materials  used  in  these  experiments,  namely,  bread  and  milk, 
over  97  per  cent  of  the  total  nitrogen  is  in  the  form  of  proteids,  and 
the  error  from  nonproteid  nitrogen  in  the  food  is  therefore  small.  In 
the  case  of  the  feces,  however,  the  kinds,  proportions,  and  composi- 
tion of  the  nitrogenous  ingredients  are  not  well  understood,  and  the 
estimate  of  "  protein"  is  at  best  very  crude.  The  errors  involved  in 
the  determination  of  carbohydrates,  by  difference,  are  too  well  known 
to  require  discussion.  Notwithstanding  these  imperfections  of  analyt- 
ical methods,  which  are  not  peculiar  to  these  investigations  but  are 
common  to  all  similar  experiments,  the  results  obtained  in  determining 
moisture,  ash,  total  nitrogen,  and  heat  of  combustion  are  believed  to 
be  reasonably  accurate,  and  the  deductions  drawn  from  them  are 
regarded  as  reliable. 

The  calorific  value  or  heat  of  combustion  of  the  various  samples  of 
food,  feces,  and  urine  was  determined  in  the  usual  way  by  means  of 
the  bomb  calorimeter.  In  the  case  of  the  milk  and  urine,  weighed 
blocks  of  cellulose  were  employed  to  absorb  the  liquid.  The  absorp- 
tion block  was  saturated,  carefully  dried,  weighed,  and  again  satu- 
rated with  a  weighed  quantity  of  material.  After  drying  at  a  tem- 
perature of  65°  C.  the  block  was  burned  in  the  calorimeter  in  the 


10 

usual  way,  a  correction  being  made  in  the  results  for  the  heat  of  com- 
bustion of  the  block  employed. 

DESCRIPTION  OF  SAMPLES  OF  FOOD  MATERIALS. 

In  the  milling  of  the  hard  spring  wheat  great  care  was  taken  to 
secure  representative  samples.  A-  in  the  former  work,  the  milling 
whs  carried  on  under  the  supervision  of  Mr.  ('.  E.  Foster,  of  Minne- 
apolis, in  one  of  the  large  flouring  mills  of  that  city.  Two  hundred 
pounds  each  of  the  three  different  kinds  of  Hour  were  obtained  from 
the  mill.  As  soon  as  the  samples  were  received  at  the  laboratory 
smaller  samples  were  drawn  for  analysis. 

For  the  experiment-  with  -oft  winter  wheat  difficulty  was  experi- 
enced in  securing  sample-  of  soft-wheat  flours  that  were  comparable 
with  the  grades  of  Hour  used  in  former  work  with  hard  spring  wheat. 
The  samples  of  hard  wheat  used  in  1899-1901  were  exhaustively 
milled  and  very  little  flour  was  left  in  the  bran  and  middlings. 

The  samples  of  soft  wheat  used  in  1(.*< )1— 2  were,  as  is  the  custom  with 
such  wheats,  less  exhaustively  milled  and  more  flour  was  left  in  the 
offals.  For  this  work  sets  of  samples  were  obtained  from  two  differ- 
ent milling  companies,  and  in  each  case  the  different  grade-  of  flour 
were  from  a  single  lot  of  wheat. 

A  description  of  the  different  sorts  of  wheat  used  in  the  experiments, 
and  of  the  different  grade-  of  flour  and  milling  products  made  from 
them,  is  here  given.  These  are  the  -amples  the  analyses  of  which  are 
reported  in  Table  1. 

In  addition  to  the  various  milling  products  mentioned,  which  are 
standard  grades,  other  grades  may  be  obtained  by  subdividing  a  grade 
or  by  mixing  or  blending  two  or  more  grades.  Many  of  the  flours 
which  are  placed  upon  the  market  are  mixtures  of  two  or  more  stand- 
ard grades  of  flour. 

X> >.  loo.  Hard  Scotch  Fife  spring  wheat,  weighing  60  pounds  per  bushel;  screened 
but  not  soured.  This  wheat  is  representative  of  the  hard  spring  wheat  grown  in  the 
North  western  wheat  regions  of  the  United  States. 

No.  154.  Entire-wheat  flour  from  hard  spring  wheat  No.  153.  This  is  the  product 
obtained  by  removing  a  portion  of  the  bran  and  grinding  the  remainder  of  the  grain. 
It  includes  the  germ  and  other  parts  of  the  offal  products  which  are  excluded  from 
the  patent  grades  of  flour.  This  flour  is  coarser  in  texture  and  darker  in  color  than 
the  patent  and  dear  grades.  The  presence  of  fine  bran  particles  prevents  perfect 
granulation.  Such  '"entire-wheat"  flour  is  sometimes  called  "  pulverized  graham" 
or  "natural  flour." 

No.  155.  Graham  flour  from  hard  spring  wheat  Xo.  153.  This  consists  of  the 
entire  wheat  kernel  including  bran,  germ,  and  offal,  ground  into  meal.  Graham  flour 
is  practically  wheat  meal;  no  sieves  or  bolting  cloths  are  employed  in  its  manufacture, 
and  coarse  particles  of  bran,  etc.,  may  be  observed  in  the  flour. 

No.  156.  Straight  patent  flour  from  hard  spring  wheat  Nc.  153.  This  includes  the 
first  and  second  patent  grades  and  the  first  clear  or  bakers"  grade  of  flour  described 
below.  Ordinarily  about  72  per  cent  of  the  s.reened  wheat  is  recovered  as  straight 
patent  flour. 


11 

No.  157.  First  patent  flour  from  hard  spring  wheat  N<>.  L53.  This  is  the  bigheert 
grade  of  patent  flour  manufactured.  Ordinarilj  aboul  56  percent  of  the  screened 
wheat  is  recovered  as  first  patent  Hour,  provided  uo  straight  flour  is  made.  Allot 
the  patent  grades  of  Hour  include  the  middlings  which,  by  the  former  processes  of 

milling,   were   not    reduced    to   flour   hut  were  included  in  the  offal    products.     The 
presence  of  the  granular  middlings  gives  a  relatively  high  protein  content  to  tin* 
patent  grades  of  flour. 
No.  158.  Second  patent  flour  from  hard  spring  wheat  No.  L53.     This  is  similar  to  firsl 

patent,  but  the  bread  made  from  it  is  a  little  darker  in  color  and  the  gluten  docs  not 
possess  quite  SO  high  a  power  of  expansion.  The  division  of  the  f  loin-  into  first,  second, 
and  straight  patent  grades  is  based  entirely  upon  mechanical  processes.  In  the  higher 
grades  of  patent  flour  the  gluten  is  distinctly  different  from  that  in  the  lower  grades. 
The  higher  the  grade  of  flour,  the  greater  the  power  of  expansion.  It  is  this  quality 
which  enables  the  flour  to  absorb  a  large  amount  of  water  and  as  a  result  produce  a 
large-sized  loaf,  and  one  of  good  physical  properties. 

No.  1")*).  First  clear  flour  from  hard  spring  wheat  No.  153.  After  the  first  and  second 
grades  of  patent  flour  are  removed  in  milling  about  12  per  cent  of  first  clear  grade 
is  obtained.  This  grade  has  a  high  protein  content,  but  the  gluten  is  different  in 
character  from  that  of  the  first  and  second  patent  grades  of  flour.  As  already 
explained,  when  the  first  and  second  patent  grades  and  the  first  clear  grade  are 
blended  as  one  product,  the  blend  is  called  straight  or  standard  patent  flour. 

No.  160.  Second  clear  or  low-grade  flour  from  hard  spring  wheat  No.  153.  After  the 
removal  of  the  first  and  second  patent  flours  and  the  first  clear  flour  about  5  percent 
of  the  original  wheat  can  be  obtained  as  second  clear  or  low-grade  flour.  This  flour 
is  much  darker  in  color  than  the  patent  and  first  clear  flours.  It  contains  gluten, 
with  a  low  power  of  expansion,  and  therefore  is  not  so  valuable  for  bread  making  as 
the  higher  grades  of  flour.  Second  clear  flour  is  characterized  by  a  high  protein 
content,  but  for  bread  making  this  protein  possesses  poor  physical  properties. 

No.  161.  Red-dog  flour  from  hard  spring  wheat.  This  is  the  lowest  grade  of  flour 
manufactured.  It  is  sometimes  used  for  feeding  animals,  and  occasionally  for  human 
food.  It  is  obtained  largely  from  the  parts  adjacent  to  the  germ  or  embryo,  and  is 
characterized  by  a  high  protein  content,  this  protein,  however,  having  different 
properties  from  that  in  the  higher  grades  of  flour.  It  possesses  but  little  power  of 
expansion,  and  the  bread  made  from  this  grade  of  flour  is  dark  in  color  and  poor  in 
quality,  at  least  as  regards  its  physical  properties.  In  the  process  of  milling  the 
wheat  germ  is  not  included  in  the  higher  grades  of  flour,  because  its  protein  is  not 
composed  of  gliadin  and  glutenin.  Furthermore,  the  germ  ferments  readily,  and 
thus  when  present  in  flour  has  a  tendency  to  render  it  unsound.  Ordinarily  from  5 
to  8  per  cent  of  the  screened  wheat  is  excluded  as  germ.  This  is  utilized  for  the 
preparation  of  breakfast  foods,  for  blending  with  other  cereal  food  products,  and  for 
other  purposes.  Frequently,  however,  the  wheat  germ  finds  its  way  into  the  shorts 
and  is  used  for  cattle  feed. 

No.  162.  Wheat  shorts  or  middlings  from  hard  spring  wheat  No.  153.  About  11.5 
to  12  per  cent  of  the  cleaned  wheat  is  recovered  as  shorts,  which  consist  of  the  fine 
bran  that  has  been  more  or  less  completely  pulverized.  When  the  wheat  germ  is 
recovered  with  the  shorts,  the  product  is  known  as  middlings.  Such  "middlings" 
must  not  be  confused  with  the  middlings  obtained  when  wheat  is  milled  by  the  old 
process.  As  previously  stated,  the  material  termed  middlings  in  the  old  process  is 
now  reduced  and  recovered  in  the  various  grades  of  patent  flour. 

No.  163.  Bran  from  hard  spring  wheat  No.  153.  This  consists  of  the  coarsely  gfc  >und 
episperm  or  outer  covering  of  the  wheat  kernel.  Ordinarily  from  13  to  15  per  cent 
of  the  cleaned  wheat  is  recovered  as  bran. 


12 

No.  L64.   Entire-wheal  bread.     This  was  made  of  the  floor  from  which  sample  No. 
L54  was  taken. 
No.  L82.  Graham  bread.     Thia  was  made  of  the  floor  from  which  sample  No.  155 

Was  taken. 

Nos.  L99  and  217.  Straight  patent  flour  bread.  In  making  this  bread  flour  was 
osed  from  which  sample  No.  L56  was  taken. 

Nos.  165,  181,  198,  and  216.  Milk.     Mixed  milk,  used  in  the  digestion  experiments. 

N<».  218.  Cleaned  soft  winter  wheat,  from  Goshen,  Ind.,  prepared  for  milling,  of 
go<»<l  quality,  and  weighing  60  pounds  per  bushel.  The  sample  analyzed  was  ground 
in  the  laboratory  in  a  Maercker  mill. 

No.  221.  Mixed-grade  flour,  ground  from  soft  winter  wheat  No.  218,  and  consisting 
hugely  of  straight  flour  with  some  lower  grades  and  a  little  germ.  As  already 
explained,  with  exhaustive  milling  about  72  per  cent  of  the  screened  wheat  is  recov- 
ered as  straight  flour,  the  grade  most  extensively  used  for  bread  making.  If  a  lower 
percentage  of  wheat  is  recovered  as  flour,  the  sample  is  ranked,  commercially,  as  a 
higher  grade  of  patent  flour  because  of  its  lighter  color  and  other  characteristic  phys- 
ical properties.  This  sample,  No.  221,  was  not  strictly  a  straight  grade  flour,  but 
was  more  properly  a  blend. 

No.  222.  Entire-wheat  flour,  ground  from  soft  winter  wheat  No.  218,  after  remov- 
ing a  small  amount  of  bran.  This  sample  was  different  from  the  entire  wheat  used 
in  former  w'ork  with  hard  wheat;  it  had  more  of  the  characteristics  of  graham.  It 
wras,  however,  more  finely  pulverized  than  the  graham  flours  used  in  the  experi- 
ments made  in  1899-1901. 

No.  267.  Middlings  obtained  in  the  milling  of  the  straight-grade  flour  No.  221, 
from  soft  winter  wheat  No.  218.  Middlings  include  the  fine  particles  of  bran  and 
germ,  and,  in  case  the  wheat  is  not  exhaustively  milled,  a  small  amount  of  the  low- 
est grades  of  flour. 

No.  268.  Bran,  from  soft  winter  wheat  No.  218. 

No.  237.  Soft  winter  wheat,  of  good  quality,  from  North  Lansing,  Mich.,  weighing 
59  pounds  per  bushel,  cleaned  and  prepared  for  milling. 

No.  240.  Straight  grade  or  standard  patent  flour,  milled  from  soft  wheat  No.  237. 
From  the  analysis  of  the  flour  and  the  appearance  of  the  offals,  it  would  seem  that 
this  flour  contained  somewhat  less  than  72  per  cent  of  the  original  wheat.  It  should 
be  classed  as  a  high  grade  rather  than  as  a  straight-grade  flour.  It  possessed  good 
bread-making  qualities,  but  required  more  thorough  mixing  and  kneading  than 
hard-wheat  flours. 

No.  238.  Middlings,  from  soft  winter  wheat  No.  237,  obtained  in  milling  flour  No.  240. 

No.  239.  Bran,  from  soft  winter  wheat  No.  237,  obtained  in  milling  flour  No.  240. 

No.  241.  Entire- wheat  flour,  prepared  from  soft  winter  wheat  No.  237. 

No.  242.  Graham  flour,  obtained  from  soft  winter  wheat  No.  237. 

No.  223.  Mixed-grade  flour  bread.  This  was  made  of  the  flour  from  which  sample 
No.  221  was  taken. 

No.  231.  Entire-wheat  flour  bread.  This  was  made  of  the  flour  from  which  sample 
No.  219  was  taken. 

No.  244.  Straight  patent  flour  bread.  In  making  this  bread  flour  was  used  from 
which  sample  No.  240  wTas  taken. 

No.  251.  Entire- wheat  flour  bread.  This  bread  was  made  of  the  flour  from  which 
sample  No.  241  was  taken. 

No.  260.  Graham-flour  bread.  The  graham  flour  used  was  the  lot  from  which 
sample  No.  242  was  taken. 

COMPOSITION  OF  SAMPLES  OF  FOOD  MATERIALS. 

In  Table  1,  which  follows,  are  given  the  results  of  the  analyses  of 
the  wheat  samples,  of  the  flours  and  other  products  made  from  the 


13 


wheat,  of  the  bread  made  from  the  flours,  and  of  tlic  milk  consumed 
iii  the  digestion  experiments. 

T.mu.k  1. — Composition  of  wheats,  flows,  and  offals,  and  of  bread,  and  milk  used  in  diges- 
tion experiment*  with  hard  and  soft  wheal  breads. 


Sample 

No. 


153 
154 

iv, 
158 
157 
158 
l.V.l 
160 
161 
L62 
163 

164 
182 
199 
217 

•J  is 
219 
221 
237 
238 
239 
240 
241 
242 
267 


223 
231 
244 
251 
260 
165 
181 
198 
216 
224 
232 
243 
258 
259 


Whence  obtained. 


Water. 


Hard  wheat: 

Wheat 

Entire-wheat  Hour 

Graham  flour 

Straighl  patent  Hour 

First  patent  Hour 

Second  patent  Hour 

First  clear  Hour 

Second  clear  Hour 

Red  dog  flour 

Middlings 

Bran 

Bread  made  from — 

Entire-wheat  Hour 

Graham  Hour 

Straight  patent  flour 

Do 

Soft  wheat: 

Wheat  from  Indiana ' 

Entire-wheat  Hour | 

Mixed  grade  flour | 

Wheat  from  Michigan I 

Middlings 

Bran i 

Straight  patent  flour 

Entire-wheat  flour 

Graham  flour 

Middlings 

Bran 

Bread  made  from— 

Mixed  grade  flour 

Entire-wheat  flour 

Straight  patent  flour 

Entire-wheat  flour 

Graham  flour 

Milk,  composite  sample 

do 


.do 
.do 
.do 
.do 
.do 
.do 
.do 


/•/  /•  cent 
10.41 
13.51 
13.  a 

12. 38 

12. 16 

;■-».(»'., 

H.92 

10.40 
10.26 
10.17 

11. 17 

40.97 
42.68 
38.77 
37.37 

8.09 

9.60 

10.30 

10.25 

7.86 

8.74 

10.97 

11.01 

11.23 

9.76 

10.94 

39.56 
39.50 
36.87 
37.62 
38.12 
87.81 
87.27 
87.  59 
87.14 
87.00 
86.56 
87.34 
87.67 
86.50 


Protein.a 


Pn  r  a  "I. 
L5.50 
13.72 
14.21 

13.60 
13.31 
13. 05 

17.7:; 
20.00 
21.83 
18.64 
17.10 

9.32 
9.54 
9.63 
9.74 

13.16 
12.80 
12.30 
12.34 
17.91 
14.96 
10.92 
12.01 
12.24 
18.34 
16.72 

8.01 
8.53 
7.59 
8.33 
8.36 
3.25 
3.13 
3.04 
3.38 
3.31 
3.32 
2.99 
3.00 
3.25 


Fat. 


<  Sarbo- 
hydratea 


Per  a  nL 

1.69 

2. 01 
1.30 

1.21 
1.37 
1 .  98 
3.17 
6.10 
6.04 
4.23 

.19 
.29 
.04  I 

.26  I 

1.52  ! 
1.54 

.93 
1.35 
5.18 
4.41 

.50 
1.53 
1.41 
4.65  I 
4.42 

.60  ' 

1.02  ] 
.38 


l'i  r  a  nL 
69.  B8 
70. 10 
68.  56 
72.04 
72.93 
73.03 
67.37 
64.24 
57.  72 
59.  72 


48.75 
46.10 
51.06 
52. 12 

75.38 
74.40 
75.  94 
74.  23 
fri.09 
65.78 
77. 15 
74.17 
73.27 
64.05 
61.20 

51. 32 
49.49 
54.67 


Ash. 


l'i  r  n  nl. 

L.98 

J.  nl 
.  68 
.39 

.  n; 

1.00 
2.19 
4.09 
5.  13 
7.31 


Eeal  of 
combus- 
tion pei 
nam, 
deter 
mined. 


.50 

.."-I 

1.85 
1.66 

.53 
1.83 
3.96 
6.11 

.46 
1.28 
1.85 
3.20 
6.72 

.51 

1.46 

.49 


Calories. 
L023 
3.877 
3.971 
3.861 
3.960 
3.904 
4. 072 
1.  112 
4.430 
L314 
4.187 

2.535 
_'.  195 
2.594 

2.647 

4.090 
4.020 
4.010 
4.000 
1.256 
4.108 
3.799 
3.  960 
3.906 


1.08 

51.70 

1.27 

.87 

51.20 

1.45 

3.80 

4.34 

.80 

4.00 

1.71 

.89 

3.82 

4.81 

.74 

4.15 

4.57 

.76 

4.38 

4.52 

.79 

4.67 

4.68 

.77 

4.09 

4.81 

.  77 

3.85 

4.75 

.73 

4.45 

5.03 

.77 

2. 710 

2.640 

2. 610 

2.690 

2. 620 

.700 

.746 

.  729 

.744 

.780 

.813 

.742 

.735 

.777 


a  In  all  samples  except  milk,  protein  is  Nx5.  70;  in  milk  it  is  Nx6.  26. 

The  hard  Scotch  Fife  spring  wheat  selected  for  the  experiments 
(sample  No.  153)  was  characterized  by  a  very  high  protein  content, 
namely,  15.5  per  cent.  In  an  earlier  publication  of  this  Department 
showing  the  average  composition  of  a  large  number  of  American  feed- 
ing stuffsa  the  protein  content  of  wheat  is  given  as  11.9  per  cent.  The 
highest  percentage  of  protein  there  recorded  is  17.2  per  cent  and  the 
lowest  8.1  per  cent.  It  will  be  observed  that  tin4  wheat  from  which 
these  flour  samples  were  obtained  contained  nearly  this  maximum 
amount  of  proteid  material.  In  the  investigations  with  hard  wheat 
previously  reported,6  the  wheat  employed  contained  12.(35  per  cent 
protein.     The  average  amount  of  protein  in  the  same  variety  of  wheat 

«U.  S.  Dept,  Agr.,  Office  of  Experiment  Stations  Bui.  No.  11,  p.  17. 
&U.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Bui.  No.  101. 


14 

is  found  to  vary  materially  from  year  to  year,  depending  among  other 
things  upon  the  amount  of  rainfall  and  the  climatic  conditions  under 
which  the  wheat  has  matured.  The  wheat  crop  produced  in  the  north- 
wotcrn  United  States  in  1900  was  unusually  rich  in  protein.  The 
rainfall  and  climatic  conditions  seemed  to  be  particularly  favorable  for 
producing  wheat  and  other  grains  with  a  high  nitrogen  content.  While 
the  wheat  employed  in  this  investigation  contained  somewhat  more 
protein  than  is  found  in  average  wheat,  in  the  author's  opinion  the 
percentage  is  no  greater  than  in  average  wheat  grown  in  the  north- 
western United  States  in  1900.  All  of  the  flour  samples  from  this 
wheat  were  relatively  richer  in  protein  than  those  in  similar  investi- 
gations with  hard  wheat  in  1898-1W,  owing  to  the  high  nitrogen  con- 
tent of  the  wheat.  The  differences  in  the  protein  content  of  the  several 
grades  of  Hour  ground  from  the  wheat  were  comparatively  small. 

There  was  a  higher  percentage  of  fat  in  the  middlings  than  in  the 
bran,  owing  to  the  presence  of  the  germ  in  the  former.  Red-dog  flour 
is  the  richest,  as  regards  both  fat  and  protein,  of  the  products  ground 
from  the  wheat.  In  the  case  of  the  patent  and  clear  grades  of  flour, 
the  heat  of  combustion  as  determined  was  found  to  agree  closely  with 
the  heat  of  combustion  obtained  by  calculation,  using  the  usual  factors, 
namely,  9.3  calories  per  gramrt  for  fat,  5.9  for  protein,  and  I:.  2  for 
carbohydrates.  As  pointed  out  in  a  previous  report,6  the  percentage 
of  ash  in  the  various  products  of  wheat  was  lowest  in  the  first 
patent  flour  and  highest  in  the  red-dog  flour.  Each  grade  of  flour, 
beginning  with  the  first  patent,  was  found  to  contain  proportionally 
more  ash  than  the  preceding  grade.  In  fact,  as  noted  previously,  the 
grade  of  flour  can  be  determined  from  the  amount  of  ash  present.  In 
the  analyses  reported  above  the  ash  content  is  greater  than  in  the 
samples  employed  in  the  earlier  work  with  hard  wheat  in  this  labora- 
tory. There  appears  to  be  a  close  relationship  between  the  amounts 
of  ash  and  protein  present  in  flour  and  other  milled  products  of  wheat, 
any  material  increase  in  protein  being  accompanied  by  a  correspond- 
ing increase  in  mineral  matter.  This  has  often  been  attributed  to  the 
phosphorus  associated  with  the  proteids.  Late  work  of  Osbornec 
indicates  that  the  total  amount  of  phosphorus  in  wheat  proteids  is 
too  small  to  account  for  the  increase  in  mineral  matter  just  alluded  to. 

The  distribution  of  the  nitrogen  and  ash  constituents  of  the  wheat 
berry  has  been  frequently  studied,  and  it  is  interesting  to  note  some 
comparatively  recent  American  work  on  the  subject,  particularly  as 
the  investigations  were  made  with  wheats  grown  in  the  United  States, 
which  are  therefore  directly  comparable  with  the  wheats  used  in  the 
investigation  reported  in  this  bulletin. 

Mrs.  Ellen  H.  Richards  and  Miss  Lottie  A.  Bragg d  studied  the  distri- 

"  V.  s.  Dept  A<:r.,  Office  of  Experiment  Stations  Bui.  101,  p.  V2.  &Ib.,  p.  9. 

c Connecticut  State  Station  Bpt.  1900,  p.  464.  ^Teeh.  Quart.,  3  (1890),  p.  246. 


15 

bution  of  nitrogen  and  phosphorus  in  winter  and  spring  wheat  and 
their  milling  products,  in  both  cases  the  milling  products  having  been 
ground  from  the  same  lots  of  wheat.  The  results  obtained  are  shown 
in  the  following  table,  which  includes  also  values  for  protein  obtained 
by  multiplying  the  figures  for  nitrogen  by  6.25: 

Table  2.     Nitrogen  and  phosphorus  in  wheat  and  its  milling  products. 


Milling  products. 


st.  Louis  winter  wheat: 

Whole  wheal 

Royal  patent  Hour  . . 

Extra  I'ancx  Hour .. . 

Low-grade  Hour 

Middlings 

Bran 

Minnesota  Bpring  wheat: 

Whole  wheal 

Patent  flour 

Bakers'  flour 

Shorts 

Bran 


Water. 

Phoa 
phorus. 

Nitrogen. 

I'i  r  a  ill. 

/'/   /'    I'l   III. 

fi  r  a  nl. 

L2.86 

0.262 

1.87 

18.37 

.061 

1.39 

lJ.r.i 

.  LOO 

1.78 

1 1 .  94 

.100 

2.08 

11.21 

.  ■!■>;> 

2.73 

12.  15 

.  828 

2.  62 

11.09 

.230 

2.24 

L2.29 

.050 

2.10 

12. 11 

.091 

2.40 

11.27 

.660 

2.  78 

11.23 

.830 

2. 55 

Protein 


/■<  r  '■'  Hi. 
11.7 
-.7 
11.1 
L3.0 
17.1 
16.4 

14.0 
13.1 

15.0 
17.4 
15.9 


The  figures  in  the  table  indicate  that,  while  a  larger  part  of  the  protein 
is  recovered  in  the  flour  than  is  the  case  with  the  phosphorus,  there  is, 
nevertheless,  a  parallelism  in  the  proportion  of  protein  and  phosphorus 
in  the  different  milling  products. 

At  the  Arkansas  Experiment  Station,  Teller a  made  a  very  thorough 
and  detailed  study  of  the  ash  constituents  of  a  sample  of  locally  grown 
medium  hard  winter  wheat  and  its  milling  products.  In  milling  3,000 
pounds  of  uncleaned  wheat,  1.83  per  cent  was  recovered  as  screenings 
and  0.33  per  cent  as  tailings,  the  percentage  of  milling  products  being 
as  follows:  Patent  flour  25.80,  straight  flour  42,  low-grade  flour  3.87, 
dust  room  contents  1.17,  ship  stuff  1.13,  and  bran  23.80.  The  loss  of 
material  in  grinding — that  is,  the  material  unaccounted  for — was 
therefore  only  0.07  per  cent. 

The  principal  ash  constituents  and  the  sulphur  and  nitrogen  in  the 
whole  wheat  and  the  different  milling  products  were  as  follows: 

Table  3. — Ash  constituent*  and  nitrogen  of  winter  wheat  and  its  milling  products. 


Milling  products. 


Wheat 

Patent  flour 

Straight  flour 

Low-grade  flour 

Dust  room  material 

Ship  stuff 

Bran 


Total 
ash.k 


Per  ct. 

1.62 

.31 

.40 

.70 

2.50 

3.08 

5.25 


Silica. 


Per  ct. 
1.04 
2.33 
1.28 

.50 
1.34 

.49 


In  total  ash. 


Ferric 
oxid. 


Per  ct. 
0.27 
.47 
.26 
.25 
.30 
.37 
.27 


Potash. 


Per  ct. 
29.70 
38.50 
36.31 
32.27 
30.85 
28.03 
28.19 


Lime. 


Per  ct. 
3.10 
5.59 
5.  65 
1.  51 
3.53 
2.80 
2.50 


Mag- 
nesia. 


Per  ct. 
13.23 
4.39 
6.44 
9.33 
12.90 
13.27 
14.76 


Phos- 
phoric 
acid. 


Per  ct. 
62.14 

48.05 
49.  32 
53.10 
49.94 
54.62 
52.81 


Sul- 
phur. 


Per  ct. 
0.13 
.09 
.10 
.16 
.15 
.17 
.21 


Nitro- 
gen. 


Pi  r  a. 
1.96 
1.54 
1.75 

2.13 

2.17 
2.78 
2.73 


a  Arkansas  Station  Bui.  42,  pts.  1.  2. 

*>This  sum  includes  values  which  are  given  for  alumina,  chlorin,  zinc,  and  sulphur  trioxid.  which 
are  not  quoted  in  the  table.  The  author  regards  the  values  for  sulphur  present  in  the  different 
materials  as  more  reliable  than  those  for  sulphui  trioxid  in  the  ash.  owing  to  a  probable  volatilization 
of  sulphur  in  burning  to  obtain  the  ash.  The  other  constituents  omitted  are  not  of  much  importance, 
the  alumina  and  zinc  being  accidentally  present. 


16 

'Feller  points  out  that  about  87.5  per  cent  of  the  entire  phosphoric 
acid.  78.5  percent  of  the  potash,  and  87.5  per  cent  of  the  nitrogen 
present  iu  the  wheat  berry  are  recovered  in  the  milling  products 
ordinarily  used  as  cattle  feeds.  As  will  be  seen  from  the  above  table, 
the  percentage  of  phosphoric  acid  increases  as  the  grade  of  flour 
decreases,  being  least  in  the  patent  flour  and  greatest  in  low-grade 
flour,  the  proportion  present  in  the  latter  being  greater  than  in  any  of 
the  milling  products  except  ship  stufl;  in  other  words,  as  shown  by  these 
figures,  the  phosphoric  acid  content,  generally  speaking,  increases  in 
passing  from  the  center  of  the  wheat  berry  to  the  outer  layer,  the 
inner  portion  yielding  the  fine  flour  and  the  outer  portion  the  bran. 
The  table  also  shows  that  in  the  various  milling  products  the  propor- 
tion of  nitrogen  (and  hence  that  of  protein,  since  the  latter  is  computed 
by  multiplying  nitrogen  by  a  constant  factor)  varies  in  practically  the 
same  way  as  the  phosphorus. 

The  parallelism  between  protein  and  phosphorus,  which  was  spoken 
of  above,  is  borne  out  by  the  analytical  data  quoted,  though  it  does 
not  necessarily  follow  that  the  phosphorus  present  occurs  in  the  true 
proteids. 

As  a  whole,  it  has  been  the  aim  in  the  experiments  conducted  at  the 
University  of  Minnesota  to  include  standard  types  and  varieties  of 
hard  and  soft  wheat  flours,  milled  under  different  conditions.  The 
differences  in  the  percentages  of  flour  recovered  from  the  wheat  used 
necessarily  make  slight  differences  in  the  composition  and  character- 
istics of  the  grades  of  flour  obtained.  The  soft  wheat  products  were 
of  different  character  from  the  samples  of  similar  products  from  hard 
wheat.  The  hard  wheats  had  been  exhaustively  milled,  as  is  the 
usual  custom,  in  one  of  the  large  mills  of  Minneapolis,  while  the  soft 
winter  wheats  were  ground  by  mills  of  smaller  capacity  using  some- 
what different  milling  systems,  and,  as  is  the  general  commercial  prac- 
tice, were  less  exhaustively  milled. 

In  general,  the  flours  from  soft  wheat  were  somewhat  similar  to, 
though  not  in  every  respect  like  those  from,  hard  wheat,  because  of 
the  differences  in  the  kinds  of  wheat  used  and  percentages  of  flour 
recovered.  The  graham  flour  contained  the  largest  percentage  of  pro- 
tein, fat,  and  ash,  while  the  patent  grades  of  flour  contained  the  small- 
est amounts  of  these  ingredients.  A  noticeable  difference  in  the 
mechanical  composition  of  the  three  grades  of  soft  wheat  flour  was 
observed.  With  the  process  of  milling  followed,  some  granular  mid- 
dlings were  left  in  the  offals  which  would  have  been  recovered  in  the 
straight  and  other  grades  of  flour  with  more  exhaustive  milling.  This 
results  in  a  straight-grade  flour  containing  slightly  less  protein  than 
the  product  of  exhaustive  milling,  as  the  granular  middlings  are  rich 
in  this  nutrient.     The  particles  or  granules  of  the  graham  flour  were 


17 

much  larger  than  those  of  cither  the  entire-wheat  <>r  the  straight-grade 
flour.  The  comparative  sizes  of  granules  from  graham,  entire-wheat, 
and  straight-grade  flours  ground  from  soft  wheat  are  shown  in  the 
micro-photographs  reproduced  in  Plate  I.  figs.  1  and  2,  and  Plate  II, 
fig.  L,p.  48. 

COMPOSITION   OF   FECES   AND  URINE    OBTAINED    IN   DIGESTION 

EXPERIMENTS. 

The  composition  of  the  dry  matter  of  the  feces  from  the  digestion 

experiments  is  given  in  Table  4,  while  Table  5  records  the  amount. 
specific  gravity,  and  percentage  of  nitrogen  of  the  urine. 
A  description  of  the  samples  of  feces  and  urine  follows: 

Nos.  178,  199,  180,  195,  196,  197,  213,  214,  and  215  represent  the  feces  which  were 
obtained  in  the  digestion  experiments  with  hard  spring  wheat  products. 

N<.s.  225,  22(1.  227.  233,  2:54.  2:55,  245,  24(5,  247,  252,  25:],  254.  261,  202,  and  263,  the 
feces  which  were  obtained  in  the  digestion  experiments  of  1901-2  with  soft  winter 
wheat. 

Nos.  166-177,  183-194,  and  200-212,  the  urine  from  the  digestion  experiments  with 
hard  spring  wheat  products. 

Nos.  22S,  229,  2:10,  236,  237,  238,  248,  249,  250,  255,  256,  257,  264,  265,  and  266,  the 
urine  obtained  in  the  experiments  with  soft  winter  wheat. 

Table  4. — Composition  of  dry  matter  of  feces  from  digestion  experiments  with  hard  and 

soft  wheat  breads. 


Sample 
No. 


ITS 
179 
180 
195 
196 
197 
213 
214 
215 

225 
226 
227 
233 
234 
235 
245 
246 
247 
252 
253 
254 
261 
262 
263 


Whence  obtained. 


Experiments  with  hard  wheat 

Experiment  No.  242 

Experiment  No.  243 

Experiment  No.  244 

Experiment  No.  245 

Experiment  No.  246 

Experiment  No.  247 

Experiment  No.  248 

Experiment  No.  249 

Experiment  No.  250 

Experiments  with  soft  wheat: 

Experiment  No.  309 

Experiment  No.  310 

Experiment  No.  311 

Experiment  No.  312 

Experiment  No.  313 

Experiment  No.  314 

Experiment  No.  315 

Experiment  No.  316 

Experiment  No.  317 

Experiment  No.  318 

Experiment  No.  319 

Experiment  No.  320 

Experiment  No.  321 

Experiment  No.  322 

Experiment  No.  323 


Protein 

(NX  6.25) 


Per  <■/  ,ii. 
25 
37 

(HI 

2.". 

Ill 

(17 


Fat. 


Per  ci  nt . 


Carbo- 
hydrates. 


Ash. 


Heat  of 
combus- 
tion per 
gram 

•  IcttT- 

mined. 


Pi  v  <-,  nt.     Per  n  ,it. 


12.  26 

34.42 

23.  07 

7.  45 

35.37 

28.81 

7.44 

41.35 

26.  21 

S.  70 

50.16 

17.89 

5.61 

47.59 

23.  49 

6.41 

50.48 

21.  11 

17.46 

25.  02 

27.  58 

11.44 

26. 42 

33.58 

9.30 

36.47 

30.29 

17.04 

45. 15 

23.  71 

15.  84 

38. 92 

23.41 

9.10 

39.40 

24.75 

5.36 

60.  48 

19.85 

10.  32 

55.98 

16.94 

4.32 

56.51 

19.11 

8.58 

43.99 

24.82 

13.13 

38.92 

24.  82 

15. 26 

32. 59 

26. 81 

5.31 

56.28 

20.  47 

11.65 

46.38 

20.97 

6.00 

51.76 

23.  57 

6.44 

57.06 

17.00 

13.98 

51.14 

17.02 

8.25 

52.68 

19.94 

Calories. 

4. 63S 
4.070 
4.:;.->i 
•1.  U5 

3.  960 
4.170 

4.  720 
4.265 
4.654 

5.030 
5.300 
4.400 
4.340 
4.  120 
4. 160 
5.050 
5.160 
5.360 
4.290 
4.410 
3.990 
4.  220 
4.  470 
4.170 


19047— No.  126—03- 


18 


Table  5.  -Amount, 


specific  gravity,  ",,<!  nitrogen  of  wrim  from  digestion  > 
hard  "ml  soft  wheal  breads. 


xpt  run,  i, ts  with 


Sample  Subject 


1 66 
169 
172 
175 

170 

17:; 
176 

168 

171 
174 

177 

183 

186 
189 
192 

184 
1-7 
190 
193 

185 
188 
191 

194 

200 
204 
207 
210 

201 
206 

208 
211 


206 
209 

•J  12 


229 
230 
236 
237 
-  - 
248 
249 

256 

257 
265 


Whence  obtained. 


Experiments  with  hard  wheat: 
Experiment  N<>.  242— 

First  day 

ad  day 

Third  day' 

Fourth  day 

Experiment  No.  243— 

First  day 

Second  day 

Third  day 

Fourth  day 


™  £££  »««*<» 


Experiment  No. 24 1- 

First  day 


Second  day 

Third  day ' 

Fourth  day 

Experiment  No.  245 — 

First  day 

Sea  >nd  day 

Third  day' 

Fourth  day 

Experiment  No.  246 — 

First  day 

Second  day 

Third  day 

Fourth  day 

Experiment  No.  247 — 

First  day 

Second  da  y 

Third  day 

Fourth  day 

Experiment  No. 248 — 

First  day 

Second  da  v 

Third  day' 

Fourth  day 

Experiment  No.  -49 — 

First  day 

Second  day 

Third  day 

Fourth  day 

Experiment  No.  250— 

First  day 

Second  day 

Third  day 

Fourth  day 

Experiments  with  soft  wheat: 

Experiment  No.  309 

Experiment  No.  310 

Experiment  No.  311 

Experiment  No.  312 

Experiment  N<  >.  313 

Experiment  No.  314 

Experiment  No.  315 

Experiment  No.  316 

Experiment  No.  317 

Experiment  No.  318 

Experiment  No.  319 

Experiment  No.  320 

Experiment  No.  321 

Experiment  No.  322 

Experiment  No.  323 


L,  368.0 
1,350.0 
1.  163.6 
1,326.0 

L,  805,0 

2.112.0 
2,298.0 
2,248.0 

1,991.0 
1,720.0 
1,679.0 
1,947.0 

1 .  27i i.  II 
1.210.0 
1.212.0 
1.102.0 

1,943.0 

1 .  732.  II 
2, 188. 0 
2,368.0 

1,851.0 
1,581.0 
1,614.5 
1,338.0 

1,124.0 
1.077.0 
1,068.0 
1,110.0 

1, 943. 0 
1,698.0 
2,182.0 

2.  023.  U 

1.123.0 
1.242.0 
1,601.0 
2. 463.  0 

6.023.1 
4,296.2 
4.  486.  2 
5, 652. 9 
5,201.7 
4,115.6 
7,317.4 
6, 556.  6 
1.747.6 

-- 
6.910.1 
5,476.6 
•">.  210.1 
1,532.0 


1.026 
1.023 
1.027 

1.029 

1.016  j 
1.016 

1.015 
1.017 

1.020 
1.021 
1.025 
1.028 


I 

1.030  j 
1.030  I 
1.030 
1.028 

1.015 

1.015 
1.015 

1.014 

1.024 
1.025  ' 
1.027 
1.027 

1.027 
1.031 
1.030 
1.029 

1.014 
1. 015 
1.015 
1.014 

1.028 

1.026 
1.022 
1.016 


L5fi 

1.4"- 

1.74 

.95 

1.00 


1.3n 
1.41 
1.  72 

1.4-. 

1.82 

l.7y 
1.84 
1.88 

1.03 
1.01 


1.72 
1.7-S 
1.91 

1.77 
2.10 
1.90 
2.04 

1.02 

1.00 

.97 

.97 

1.82 
1.81 
1.56 
1.07 


1.016 

1.10 

1.020 

1.50 

1.019 

1.31 

1.019 

1.21 

1.020 

1.41 

1.02-2 

1.4s 

1. 016 

1.19 

1.019 

1.41 

1.020 

1.39 

1.016 

1.07 

1.020 

1.47 

1.021 

1.61 

1.020 

1.41 

1.020 

1.16 

1.022 

1.80 

EXPERIMENTAL  METHODS. 

The  methods  followed  in  all  of  the  experiments  here  reported  are 
practically  identical  with  those  described  in  detail  in  the  previous 
publication"  already  referred  to.  and  need  only  be  briefly  outlined. 

The  bread  from  the  different  sorts  of  flour  was  eaten  with  milk:  the 
amount  of  cither  was  not  limited,  but  the  quantities  eaten  at  each  meal 
were  recorded.     The  separations  of  the  feces  were  made  by  means  of 


I.  B.  Dept  A-r..  Office  of  Experiment  Stations  Bui.  101. 


19 

charcoal  taken  with  a  meal  of  bread  and  milk,  which  gives  feces  of  a 

characteristic  color  and  consistency.  The  digestibility  of  the  nut  rients 
of  the  diet  as  a  whole  was  taken  as  the  difference  between  the  amounts 

in  the  food  and  those  in  the  feces,  no  attempt  being  made  to  determine 
the  metabolic  products  of  the  feces.'' 

In  order  to  compute  the  digestibility  of  the  nutrients  of  the  bread 
alone,  it  was  assumed  that  97  per  cent  of  the  protein.  95  per  cenl  of 
the  fat,  and  98  per  cent  of  the  carbohydrates  of  milk  were  digested. 
The  undigested  nutrients  of  the  milk  as  calculated  by  the  use  of  these 
factors  subtracted  from  the  nutrients  of  the  total  feces  give  the  esti- 
mated undigested  nutrients  from  bread,  which,  subtracted  from  the 
total  nutrients  of  the  bread,  give  the  digestible  nutrients  in  bread. 
The  latter,  divided  by  the  total  nutrients  in  the  bread,  give  the  coeffi- 
cients  of  digestibility  of  bread  alone. 

The  values  used  for  the  digestibility  of  the  nutrients  of  milk  have 
been  deduced  from  the  results  of  a  large  number  of  digestion  experi- 
ments with  milk.  P^ven  if,  in  the  experiments  here  reported,  the  diges- 
tibility of  the  milk  nutrients  varied  from  these  assumed  coefficients, 
the  figures  for  the  digestibility  of  the  nutrients  of  the  different  kinds 
of  bread  are  still  strictly  comparable  because  the  same  factors  for 
milk  were  used  in  all  cases. 

As  has  been  already  explained,6  the  energy  of  the  estimated  feces 
from  bread  alone  was  computed  by  proportion  from  the  energy  of  the 
total  feces.  The  ratio  of  the  heat  of  combustion  of  the  bread  feces 
as  computed  b}-  factors  to  the  actual  energ}T  was  assumed  to  be  the 
same  as  the  ratio  of  the  computed  energy-  of  total  feces  to  the  heat  of 
combustion  as  determined. 

Although  the  energ}^  of  the  urine  was  determined,  in  the  calculation 
of  the  availability  of  the  energy  of  the  total  food  and  of  the  bread 
alone,  it  was  assumed,  for  the  sake  of  uniformity  with  experiments 
previously  reported,  that  1.25  calories  of  energ}T  would  appear  in  the 
urine  for  every  gram  of  digestible  protein  in  the  total  food  or  in  the 
bread  alone.  For  the  sake  of  making  an  approximate  estimate  of  the 
available  energy  in  those  experiments  where  the  digestibility  of  the 
bread  fat  could  not  be  computed,  it  was  assumed  that  90  per  cent  of 

«It  should  be  observed  that  the  results  thus  obtained  do  not  represent  actual 
digestibility.  The  true  digestibility  could  be  found  by  subtracting  from  the  ingredi- 
ents of  the  food  the  corresponding  ingredients  of  the  feces  that  come  only  from  undi- 
gested portions  of  the  food.  But  no  satisfactory  method  has  been  found  for  separating 
these  from  the  metabolic  products  in  the  feces,  which  consist  largely  of  the  residues 
of  the  digestive  juices  that  have  not  been  reabsorbed.  These  latter  represent  the 
cost  of  digestion  as  expressed  in  terms  of  food  ingredients.  What  the  results  of  these 
experiments  do  represent,  therefore,  is  the  proportions  of  the  food,  or  of  the  several 
ingredients,  that  are  available  to  the  body  for  purposes  other  than  digestion  itself. 
In  accordance  with  common  usage,  however,  the  term  digestibility,  which  indicates 
the  apparent  digestibility,  has  been  employed  here;  the  term  availability  is  some- 
times used  to  express  the  same  idea. 

&U.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Bui.  101,  p.  22. 


20 

the  fat  of  the  bread  was  digestible.  The  results  thus  found  would 
probably  be  below  rather  than  above  what  was  actually  the  case. 

As  in  the  preceding  experiments,  the  balance  of  income  and  outgo 
of  nitrogen  was  learned  by  determining  the  daily  amounts  ingested 
in  the  food  and  excreted  in  the  urine  and  feces.  In  the  experi- 
ments with  soft  winter  wheat  in  1901-2  determinations  were  also  made 
of  the  phosphoric  acid  in  the  samples  of  food,  feces,  and  urine.  Such 
data,  however,  are  reserved  for  further  study. 

The  particular  difference  between  the  digestion  experiments  given 
here  and  those  formerly  reported  is  in  the  length  of  the  experimental 
period,  this  being  four  days  long  here  and  only  two  in  the  earlier 
experiments.  The  longer  experimental  period  is  believed  to  be  pref- 
erable, because  it  is  generally  considered  that  there  is  less  danger 
of  error  due  to  uncontrollable  factors  that  may  vitiate  the  results  in 
a  short  digestion  period. 

As  is  well  known,  the  results  obtained  from  a  digestion  experiment 
are  not  absolute,  but  only  relative.  But  inasmuch  as  in  the  diges- 
tion experiments  reported  in  this  bulletin  the  object  is  to  deter- 
mine the  relative  rather  than  the  absolute  digestibility  of  three 
different  kinds  of  bread,  it  is  believed  that  the  results  obtained  are 
satisfactory  for  this  purpose,  because  whatever  error  may  be  intro- 
duced in  one  experiment  is  introduced  alike  in  all  of  an}*  given  series. 
since  the  conditions  were  kept  uniform  throughout  the  series.  While 
the  results  of  a  single  digestion  experiment  are  open  to  criticism,  the 
results  obtained  from  a  series  of  experiments  are  much  less  so  and  are 
of  value  in  determining  whether  one  food  is  more  digestible  than 
another  under  similar  experimental  conditions.  Hence  in  discussing 
the  results  obtained  from  these  digestion  experiments  they  are  con- 
sidered in  relation  to  one  another  rather  than  alone. 

DETAILS  OF  THE  DIGESTION  EXPERIMENTS  WITH  BREAD  FROM 
DIFFERENT  GRADES  OF  HARD  SPRING  WHEAT  FLOUR. 

The  details  of  the  digestion  experiments  with  hard  wheat  products 
are  given  in  the  following  pages.  Nine  digestion  experiments,  each  of 
four  days*  (or  twelve  meals')  duration  were  made  with  three  different 
subjects.  In  every  case  the  diet  consisted  of  bread  and  milk,  and  all  of 
the  experiments  were  conducted  in  the  same  manner,  except  that  bread 
made  from  a  different  kind  of  Hour  was  used  in  each  series.  In  making 
the  bread  no  shortening  or  milk  was  used,  but  simply  yeast,  flour,  salt, 
and  water. 

The  subjects  were  university  students  who  spent  from  three  to  four 
hours  each  day  at  light  muscular  work  out  of  doors.  All  had  served 
as  subjects  in  former  digestion  experiments  and  were  thoroughly 
familiar  with  the  requirements  of  such  work. 

The  experiments  were  practically  made  in  triplicate — that  is,  the 
same  kind  of  an  experiment  was  made  with  each  of  three  subjects  at 


21 


the  same  time.    TheorderiD  which  they  were  conducted  was  as  follows: 
The  firsl  scries  of  experiments  (with  entire-wheat  bread)  extended 

from  April  17  to  April  l>0,  inclusive;  the  second  series  (with  graham 
bread)  from  April  23  to  April  26,  inclusive;  and  the  third  series  (with 
bread  from  standard  patent  Hour)  from  May  1  to  May  4.  Inclusive. 
The  experiments  were  taken  up  in  this  order  because  of  the  difficulty 
experienced  in  previous  experiments  with  a  graham  bread  and  milk 
diet.  It  was  believed  that  the  investigation  could  he  conducted  to 
better  advantage  by  having  the  graham  bread  experiment  between  the 
others,  lather  than  at  the  beginning  or  close  of  the  series.  The  four 
days*  diet  of  graham  bread  and  milk  caused  a  slight  irritation  of  the 
digestive  tract  and  a  slight  attack  of  gastritis  with  two  of  the  subjects. 
The  following  tables,  Nbs.  6  to  11,  and  the  accompanying  data  show 
the  kind  of  food  consumed,  the  subject  experimented  upon,  the  body 
weight  at  the  beginning  and  at  the  close  of  the  experiment,  and  the 
date  and  duration.  Then  follow  statistics  of  the  total  nutrients  in 
the  food  and  the  feces,  and  the  heat  of  combustion  of  each,  and  after 
each  of  the  tables  statistics  are  given  of  the  income  and  outgo  of 
nitrogen  during  the  experiment. 

DIGESTION  EXPERIMENT  NO.   242. 

Kind  <>f  food. — Milk,  and  bread  made  from  entire-wheat  flour. 

Subject. — University  student  No.  1,  22  years  old,  employed  about 
four  hours  per  day  at  manual  labor. 

Wright. — At  the  beginning  of  the  experiment,  168  pounds;  at  the 
close,  168  pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
April  17,  1901. 

Table  6. — Results  of  digestion  experiment  No.  242. 


Sample 

No. 

Weight 

of 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 
combus- 
tion. 

164 
165 

Food  consumed: 

Bread 

Milk 

Grams. 
3, 550. 0 
9, 950.  0 

Grams. 
330.9 
323.4 

Grams. 

6.7 

378.1 

Grams. 

1,730.7 

431.8 

Grams. 
27.3 
79.6 

<  'ainrits. 
8,998 
6  965 

Total 

654.3 

384.8 

2, 162. 5 

106.9  I        15,963 

Feces  (water  free) 

Estimated  feces  from  food  other 
than  bread    

17* 

214.  0 

64.7 
9.7 

26.2 

73.7 
8.6 

49. 4                992 

Estimated     feces     from 
bread 

55.0 

66. 1 

Total  amount  digested 

589.6 
275  9 

358  6 

2, 088.  8 
1,665.6 

57.5           14.971 

Estimated  digestible  nutrients 
in  bread 

Coefficients  of  digestibility  of 
total  food  



Per  cent 

Per  cent. 
90.1 

.S3.  4 

Per  cent. 
93.2 

l'i  r  a  nt. 
96.6 

96.2 

Per  a  nt. 
53.8 

Per  cent. 
93.8 

Estimated  coefficients  of  diges- 
tibility of  bread 

<«  93. 0 

Proportion  of  energy  actually 
available  to  body: 
In  total  food..* 

88.2 

In  bread  alone 

a  89.1 

a  Estimated  on  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 


22 

During  this  experiment  the  subject  eliminated  5,508  grams  urine, 
containing  88.42  grams  nitrogen.  The  average  nitrogen  balance  per 
dav  was  therefore  as  follows:  Income  in  food.  27.47  grams;  outgo  in 
mine.  22.10  grams  and  in  feces,  2.59  grams,  implying  a  gain  of  2.78 
grams  nitrogen,  corresponding  to  17.4  grams  protein. 

DIGESTION  EXPERIMENT  NO.   243. 

KmdoffoocL      Milk,  and  bread  made  from  entire-wheat  flour. 
Subject. — University  student  No.  2,  22  years  old,  employed  about 

four  hours  per  day  at  manual  labor. 

Wright. — At  the  beginning  of  the  experiment,  150  pounds;  at  the 
close,  155  pounds. 

I  >>i  ration.  —  Four  days,  with  twelve  meals,  beginning  with  breakfast 
April  17,  1901. 

Table  7. — Results  of  digestion  experiment  No.  ./■/'•/. 


Sample 
No. 

Weight 

of 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash, 

Heat  of 
combus- 
tion. 

164 

Food  consumed: 

Grams. 

3. 101.  C 
12, 310. 0 

Grams. 

289.0 
400.1 

Grains. 

5.9 

467.8 

Grams. 
1,511.8 

534.3 

Grams, 

23.9 

Calories. 

7.8K0 

165 

Milk 

98.5  1          8,617 

Total 

Feces  ( water  free) 

Estimated  feces  from  food  other 
than  bread 

689. 1 

473.7 

2,046.1 

122.  4           16,  477 

179 

180.  0 

51.1 

12.0 

13.4 

63.  7 

10.7 

51.9                733 

Estimated       feces      from 
bread 

39.1 

53.0 

Total  amount  digested 

638.0 

249.9 

460.  3 

1,982.4 
1.  158.8 

70.5           15,744 

Estimated  digestible  nutrients 
in  bread 





Coefficients  of  digestibility  of 
total  food 

Per  cent. 

Per  cent. 

92.6 

86.5 

Pt  r  <■>  ut. 
97.2 

96.9 
96.5 

Pun nt.    Percent. 

.".7  6 

Estimated  coefficients  of  digest- 

"90.4 

Proportion  of  energy  actually 
available  to  body: ' 
In  total  food. .". 

90.7 

In  bread  alone 

a  90.0 



1 

«  Estimated  on  the  assumption  t 

hat  90  per 

cent  of  th 

e  fat  in  th 

e  bread  is 

digestible 

During  this  experiment  the'  subject  eliminated  8,463  grams  urine, 
containing  80.95  grams  nitrogen.  The  average  nitrogen  balance  per 
day  was  therefore  as  follows:  Income  in  food.  28.68  grams;  outgo  in 
urine,  20.21  grams,  and  in  feces,  2.09  grams,  implying  a  gain  of  6.35 
grams  nitrogen,  corresponding  to  39.7  grams  protein. 


23 


DIGESTION  EXPERIMENT  NO.  244. 

Kind  of  food.     Milk,  and  bread  made  from  entire-wheat  flour. 

Subject.  University  student  No.  3,  21  years  old,  employed  about 
four  hours  per  day  at  manual  labor. 

Weight. — At  the  beginning  of  the  experiment,  L61  pounds:  at  the 
close.  L60  pounds. 

Duration.  Four  days,  with  twelve  meals,  beginning  with  breakfast 
April  IT.  UXH. 

Table  8. — Results  of  digestion  experiment  No.  244> 


Sample 
No. 

Weight 

of 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 
combus- 
tion. 

164 

Food  consumed: 

Grams. 
3, 760. 0 
14,843.0 

Grams. 
350.4 

482.4 

Grams, 

7.1 
564.0 

Grams. 

1,833.1 

644.2 

Oram*. 

28.9 
118.8 

Calorie*. 
9,530 

165 

Milk  ....               

10, 390 

Total 

832.8 

571.1 

2,477.3 

147.7 

19,  920 

180 

215. 1 

53.8 
14.5 

16.0 

88.9 
12.9 

56.4                936 

Estimated  feces  from  food  other 

Estimated    feces    from 

39.3 

76.0 

Total  amount  digested 

779.0 
311.1 

555.1 

2,388.4 
1, 757. 1 

91.3           18,984 

Estimated  digestible  nutrients 
in  bread 

Coefficients  of  digestibility  of 
total  food 

Per  cent. 

Per  cent. 
93.5 

88.8 

Per  cent. 
97.2 

Per  >■'  nt. 
96.4 

95.9 

Per  cent. 
61.8 

Per  cent. 
95.3 

Est  i mated  coefficients  of  digest- 
ibility of  bread 

«  94.  3 

Proportion  of  energy  actually 
available  to  body: 

In  total  food 

90.4 

In  bread  alone 

u90.2 

<i  Estimated  on  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  7,337  grams  urine, 
containing  108.24  grams  nitrogen.  The  average  nitrogen  balance  per 
day  was  therefore  as  follows:  Income  in  food,  34.66  grams;  outgo  in 
urine,  27.06  grams,  and  in  feces,  2.15  grams,  implying  a  gain  of  5.15 
grams  nitrogen,  corresponding  to  34.1  grams  protein. 


DIGESTION  EXPERIMENT  NO.   245. 

Kind  of  food. — Milk,  and  bread  made  from  graham  Hour. 

Subject. — University  student  No.  1. 

Weight. — At  the  beginning  of  the  experiment.  168  pounds;  at  the 
close,  167  pounds. 

Duration, — Four  days,  with  twelve  meals,  beginning  with  breakfast 
April  23,  1901. 


24 


Tablb  (.».  —  Results  of  digestion  t  vperiment  No.  .'i-~>. 


Sample 
No. 

Weight 

of 
material. 

Protein. 

Pat 

Carbo- 
hydrates. 

ash. 

Heat  of 
combus- 
tion. 

182 

Pood  consumed: 

Bread  

Gram*. 
3, 342.0 
LO,  207.0 

Urn  ins. 

318.8 

319.5 

Gram*. 

9.7 
408.  3 

Grams. 
1,540.7 

480.8 

Grams. 

i»;.  :. 

Calories 
k         8.837 

181 

Milk                      

90.8            7.til4 

Total 

(538.3 

418.0 

2,021.5 

137.3 

15,951 

196 

300. 1 

69.8 
9.G 

26. 1 

■JO.  4 

150. 5 

9.fi 

53.7 

1,325 

Estimated  fecesfromfood  other 

302 

Estimated      feces      from 

GO.  2 

5.7           140.9 

1,023 

568. 5 
258.6 

391.9        1,871.0 
4.0       1,399.8 

83.6 

14,626 

Estimated  digestible  nutrients 

7,314 

Coefficients  of  digestibility  of 

Per  cent. 

Per  cent. 
B9.  1 

81.1 

Per  <■<  nt. 
93.8 

41  2 

Per  <■>  ut. 
92.6 

90.9 

Per  cent. 
60.9 

Per  cent. 
91  7 

Estimated  coefficients  of  digest- 

^7  7 

Proportion  of  energy  actually 
available  to  body: 



87.2 



83.9 

During  this  experiment  the  subject  eliminated  4,794  grams  urine, 
containing  87.79  grams  nitrogen.  The  average  nitrogen  balance  per 
day  was  therefore  as  follows:  Income  in  food,  26.74  grams;  outgo 
in  urine.  21.9.5  grams,  and  in  feces  3.79  grams,  implying  a  gain  of  1 
gram  nitrogen,  corresponding  to  6.3  grams  protein. 

DIGESTION    EXPERIMENT   NO.    246. 

Kind  of  food. — Milk,  and  bread  made  from  graham  flour. 

Subject. — University  student  No.  2. 

Weight. — At  the  beginning  of  the  experiment.  154  pounds;  at  the 
close,  152.7  pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
April  23,  1901. 

Table  10. — Results  of  digestion  experiment  No.  246. 


Sample 
No. 

Weight 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 
combus- 
tion. 

182 

Fooft  consumed: 

Bread  

Grams. 
2,855.  0 
10,568.0 

Grams. 

272.  4 
330.8 

Grams. 
8.3 

Grams. 

1    Rlfi  2 

Grams. 

39.7 
94.1 

Oaiones. 

7,123 

181 

Milk 

422.  7           4^7.  8 

7,883 

Total 

603. 2 

431.0       1,814.0 

133.  S 

15, 006 

Feces  ( water  free) 

196 

259.0 

60.4 

9.9 

14.5            123  3 

60.8 

1  026 

Estimated     feces     from 
other  than  bread 

food 

10  0 

Estimated      leces 

lrom 

.50.  5 

113.3 

Total  amount  digested 
Estimated  digestible  nut 
in  bread  

542.  S 
221.  9 

416  5 

1.690.7 
1,202.9 

73.0 

13  980 

riciits 

25 


Table  10. — Results  of  digestion  experiment  No.  ."/'•-  Continued. 


Bample 
No. 


Coefficients  oi  digestibility  of 

total  food 

Estimated  coefficients  of  diges 

tibility  of  bread 

Proportion  of  energy  actually 
available  to  body: 

In  total  food 

In  bread  alone 


Weight 
material, 


l'<  r  <■<  ni. 


Protein. 


Fat. 


Percent.    Percent. 
90.0  96.6 


SI.  5 


Carbo 
hydrates, 


l'i  r  r,  at. 

98.2 


91.4 


ash. 


Heal  oi 

«C  (II  l  1  .11- 

IlMl,. 


i'<  r  -•'  hi. 
4.6 


Per  a  nt. 

"88.9 


a  86.1 


<t  Estimated  on  the  assumption  that  90  per  cent  of  the  fal  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  8,231  grams  urine, 
containing  81.73  grams  nitrogen.  The  average  nitrogen  balance  per 
day  was,  therefore,  as  follows:  Income  in  food,  25.16  grams;  outgo 
in  urine,  20.43  grains,  and  in  feces,  2.94  grams,  implying  a  gain  of  1.79 
grams  nitrogen,  corresponding  to  11.2  grams  protein. 


DIGESTION  EXPERIMENT  NO.  247. 

Kind  of  food. — Milk,  and  bread  made  from  graham  flour. 

Subject. — University  student  No.  3. 

Weight. — At  the  beginning  of  the  experiment,  161  pounds;  at  the 
close,  157  pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
April  23,  1901. 

Table  11. — Results  of  digestion  experiment  No.  247. 


Sample 
No. 

Weight 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 

com- 
bustion. 

182 

Food  consumed: 

Bread 

Grams. 
3, 440. 0 
12,475.0 

Grams. 
328. 2 
390.5 

Grams. 

10.0 

499.0 

Grams. 

1,585.9 

587.6 

Grams. 
47.8 
111.0 

Oalories. 

8  583 

181 

Milk 

9,306 

Total 

718.7 

509.0 

2, 173.  5 

158.8 

17, 889 

Feces  (water  free) 

197 

267.7 

58.0 
11.7 

17.2 

135.1 
11.7 

57.4 

1,116 

Estimated  feces  from  food  other 
than  bread 

Estimated    feces     from 
bread 



46.3 

123.4 

Total  amount  digested 



660.7 
281.9 

491.8 

2, 038. 4 
1,462.5 

101.4 

16, 773 

Estimated  digestible  nutrients 
in  bread 

Coefficients  of  digestibility  of 
total  food 

Per  cent. 

Per  cent. 
91.9 

85.9 

Per  cent. 
96.6 

Per  '■>  ni. 
93.8 

92.2 

Per  cent. 
63.9 

Per  cent. 
93.8 

Estimated  coefficients  of  diges- 
tibility of  bread 

«90. 3 

Proportion  of  energy  actually 
available  to  body: 
In  total  food 

89.2 

In  bread  alone 



a  86  2 

a  Estimated  on  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 


26 

During  this  experiment  the  subject  eliminated  6,385  grams  urine, 
containing  L07.13  grams  nitrogen.  The  average  nitrogen  balance  per 
day  was  therefore  as  follows:  Income  in  food.  30.01  grams;  outgo  in 
urine  26.78  grams,  and  in  feces.  2.32  grams,  implying  a  gain  of  0.91 
grams  nitrogen,  corresponding  to  5.7  grams  protein. 

DIGESTION  EXPERIMENT  NO.  248. 

Kmd  of  food.     Milk,  and  bread  made  from  straight  patent  Hour. 
Subject. — University  student  No.  1. 

Weight. — At  the  beginning  of  experiment.  164  pounds;  at  the  close, 
It  14  pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
May  1,  1901. 


Table  12. — Results  of  digestion  experiment  1 

Vo.  248. 

Sample]                                                           *«§*' 

V,  .                                                                                                                        (JI 

ISO*     1                                                            material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Heat  of 
Ash.       combus- 
tion. 

Food  consumed: 

199            Bread 

19S            Milk 

Total 

Grams. 
2,575.0 
10,583.0 

Grams. 

248.0 
321.7 

Grams. 
1.0 

404.3 

Grams. 

1.314.9 

509.0 

Grams.     Calorie*. 

12.9             6,680 
78.3  J          7.715 

569.7 

405.  3 

1,823.9 

91.2           14,395 

213 

152. 0 

45.  5 
9.  G 

26.5             38.0 
20.2             10.2 

41.9 

717 

Estimated  feces  from  food  other 
than  bread 

309 

Kstima  t  ed    feces    from 
bread 

T<  »tal  amount  digested 

35.9 

27. 8 

524. 2 

,,,, 

378.8       1,785.9 
1,287.1 

4^.  3           13, 678 

Estimated  digestible  nutrients 
in  bread 

Coefficients  of  digestibility  of 
total  food 

. 

Per  cent 

92.0 

Per  cent. 

93.5 

1>>  r  cent. 
97.9 

97.9 

• 
54  1 

Per  cent. 
95.0 

Estimated  coefficients  of  digest- 

a  94.8 

Proportion  of  energy  actually 
available  to  body: ' 
In  total  food  .* 

90.5 

a  90. 9 

"  Estimated  on  the  assumption  that  90  per  cent  of  the  fat  in  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  4.378  grams  urine, 
containing  85.44  grams  nitrogen.  The  average  nitrogen  balance  per 
day  was  therefore  as  follows:  Income  in  food.  23.79  grams:  outgo  in 
urine.  21.38  grams,  and  in  feces,  1.82  grams,  implying  a  gain  of  0.59 
gram  nitrogen,  corresponding  to  3.7  grams  protein. 

DIGESTION  EXPERIMENT  NO.  249. 

Kind  of  food.  —  Milk,  and  bread  made  from  straight  patent  flour. 

Subject.  —  University  student  No.  2. 

Weight.— At  the  beginning  of  the  experiment,  152  pounds;  at  the 
close,  15H  pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
Mav  1,  1901. 


27 


Table  L3. — Results  of  digestion  experiment  No.  ./'■'. 


Sample 

Ho. 

Weight 
Of 

material. 

Protein. 

Pat. 

I 
hydrates. 

ash. 

Ibat  Of 

combue 

tioli. 

199 

Food  consumed: 

Bread 

drums. 
2,  790. 0 
ll.717.it 

Grama. 
268.  7 

Grams. 
L2 

H7.  6 

Grams. 
1.  124.6 

Grams. 

I'nlnrii*. 

198 

Milk 

Touil           

m  9 

lis.  s 

100.6 

15,779 

'Ml 

146. 8 

41.9 
10.7 

16.8 

38.8 
11.3 

49.3 

626 

Estimated  feces  from  food  other 

Estimated    feces    from 

31.2 

27.5 

583.0 
237.5 

432.0 

1,949.4 
1,397.1 

51.3 

15, 153 

Estimated  digestible  nutrients 

Coefficients  of  digestibility  of 

Per  cent. 

Per  cent. 
93.3 

88.4 

Per  cent. 
96.3 

Per  cent. 
98.1 

98.1 

Per  cent. 
51.0 

• 
96.0 

Estimated  coefficients  of  digest- 

«95.5 

Proportion  of  energy  actually 
available  to  body: 

91.4 

|"" 

«91.4 

«  Estimated  on  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  7.840  grams  urine, 
containing  77.  52  grams  nitrogen.  The  average  nitrogen  balance  per 
(lav  was  therefore  as  follows:  Income  in  food,  26.05  grams;  outgo  in 
urine,  19.38  grams,  and  in  feces,  1.68  grams,  implying  a  gain  of  4.99 
grams  nitrogen,  corresponding  to  31.2  grams  protein. 

DIGESTION  EXPERIMENT  NO.  250. 

Kind  of  food. — Milk,  and  bread  made  from  straight  patent  flour. 

Subject* — University  student  No.  3. 

Weight.—  At  the  beginning  of  the  experiment.  152  pounds;  at  the 
close,  155  pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
May  1,1901. 


Table  14. — Results  of  digestion  experiment  No.  250. 


Sample 
No. 

Weight 

of 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Seal  oi 

combus- 
tion. 

217 

•Jit; 

Food  consumed: 

Bread 

Milk 

Grams. 
3,080.0 
13,055.0 

Grams. 

300.0  , 
441.3 

Grams. 

8.0 

541.8 

Grams. 

1,605.3 

596.6 

drams. 

.       15.7 

99.2 

Calories. 

- 
9,713 

Total 

741.3 

549.8 

2,201.9 

114.9 

17, 865 



215 

167.0 

40.0 
13.2 

15.5 

60.  9 

11.9 

50.6 

777 

Estimated  feces  from  food  other 
than  bread 

Estimated     feces    from 

26.8 

49.0 

Total  amount  digested 

.... 

701.3 
273.2 

534.3 

2, 141. 0 

1,556.3 
■ - 

64.3 

17,088 

Estimated  digestible  nutrients 
in  bread 



28 


Table  14. — Results  of  digestion  experiment  No.  250 — Continued. 


Sample 
No. 

Weight 

of 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 
combus- 
tion. 

Coefficients  of  digestibility  of 

Per  cent. 

Per  cent. 
94.6 

91.1 

Per  cent. 
97.  2 

Per  cent. 
97.2 

97.0 

Per  cent. 
56.0 

Per  cent. 
95  7 

Estimated  coefficients  of  diges- 
tibility of  bread 

"94.5 

Proportion  of  energy  actually 
available  to  body: 

90.8 

"90.3 

"  Estimated  >>n  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  6,439  grams  urine, 
containing  94.25  grams  nitrogen.  The  average  nitrogen  balance  per 
day  was  therefore  as  follows:  Income  in  food,  30.70  grams;  outgo  in 
urine,  23.56  grams,  and  in  feces,  1.60  grams,  implying  a  gain  of  5.60 
grams  nitrogen,  corresponding  to  35.0  grams  protein. 

SUMMARY  OF  RESULTS  OBTAINED  WITH   HARD  SPRING  WHEAT 

PRODUCTS. 

The  following  tables  summarize  the  results  of  the  digestion  experi- 
ments with  hard  spring  wheat  products  reported  in  the  foregoing  pages. 
The  results  are  given  for  the  whole  ration  in  Table  15  and  computed 
for  the  different  sorts  of  bread  alone  in  Table  16.  For  purposes  of 
comparison,  the  results  obtained  in  previous  experiments  in  this 
laboratory  are  also  included,  as  well  as  the  average  digestibility  of 
the  different  kinds  of  bread  as  shown  by  the  result  of  all  the 
experiments. 

Table  15. — Summary  of  digestion  experiments  with  hard  spring  wheat;  digestibility  of 
nutrients  and  availability  of  energy  of  total  food. 


No.        wo- 


242 
243 
244 


245 
246 
247 


248 
249 

250 


Kind  of  food. 


Milk  and  entire  wheat  bread 

do 

do 


Average  of  3 

Average  of  3  ( 1899-1900) . 
Average  of  6 


Milk  and  graham  bread 

do 

do 


Average  of  3 

Average  of  3(1899-1900). 

Average  of  6 


Milk  and  white  bread  (standard  patent  | 

do 

....do 


Average  <»i  3 

Average  of  3  (1899-1900) 
Average  of  6 


Protein. 


Per  cent. 


Fat. 


hSSe,   *»™ 


Per  cent. 
93.2 
92.6  !  97.2 

93.5  97.2 


92.1 

89.7 


89.1 
90.0 
91.9 


90.3 
88.2 
89.3 


Per  cent. 


96.9 
96.4 


95.9 
91.7 
93.8 


93.8 
96.6 
96.6 


95.7 
91.1 
93.4 


Per  cent. 
89.2 
90.7 
90.4 


96.6 
95.1 

95.8 


92.6 
93.  2 


93.2 
91.1 
92.  2 


92.0 
93.3 
94.6 

93.5 
96.3 
97.2 

97.9 
98.1 
97.2 

93.  3 
91.4 

9-2.4 

95.7 
92.4 
9,5 

97.7 
97.6 

97  7 

90.1 
88.5 
89.3 


88.3 
86.0 
87.2 


90.5 
91.4 
90.8 


90.9 
90.3 
90.6 


29 

Table  1<>. — Summary  of  digestion  experiments  with  hard  spring  wheat;  digestibility  of 
nutrients  and  availability  of  energy  of  bread  alone. 


Expert- 

IIH'Ill 

No. 


242 
2 13 
244 


245 
246 
247 


248 
249 
250 


Subjed 

No 


Kind  of  [ood. 


Entire  wheal  bread 

....do 

....do 


Average  of  8 

Average  of  8  (i.sw-1900) 
Average  of  6 


(Iralmm  bread. 

do 

....do 


Average  of  3 

Average  of  3  (1899-1900) 
Average  of  6 


White  bread  (standard  patent). 

do 

....do 


Average  of  3 

Average  of  3  (1899-1900) 
Average  of  6 


Protein. 


p<  /■  cent. 
83.  I 
86.  6 
88.  8 


so.  •_> 
80.  1 
S3.  3 


Carbo- 
hydrates. 


i'i  r  cent. 
96. 2 
96.5 
96.  9 


81.1 
81.5 

85.9 


82.8 
77.6 
80.2 


85.  5 
88.4 
91.1 


88.3 
85.3 
86.8 


96.2 
94. 1 
95.  I 


91.  I 

92,  2 


91.5 

88.4 
90.0 


97.9 
98.1 
97.0 


97.7 
97.5 
97.6 


Energy. 


Per  a  nt. 
89. 1 
90.0 
90.  2 


s-.t.  s 
87.  6 


88.9 

85. 1 

86.2 


85. 1 
80.7 
82.9 


90.9 
91.4 
90.3 


90.1 
90.5 


It  will  be  observed  that  the  average  coefficients  of  digestibility  of 
the  protein  and  carbohydrates  and  of  the  available  energy  in  the 
ration  consisting  of  milk  and  bread  made  from  straight  patent  flour 
ground  from  hard  spring  wheat  were  larger  than  in  the  rations  of  milk 
and  entire-wheat  bread  or  milk  and  graham  bread  from  the  same  lot 
of  wheat.  Considering  the  calculated  results  for  bread  alone,  in  the 
experiments  here  reported  it  appears  that  in  the  graham  bread  the 
average  digestibilit}-  of  the  protein  is  82.8  per  cent;  of  the  carbolry- 
drates,  91.5  per  cent,  and  the  available  energy  is  85.1  per  cent.  The 
digestion  coefficients  for  the  graham  bread  are  lower  than  for  either 
the  entire-wheat  bread  or  the  straight  patent  flour  bread.  In  the  case 
of  the  bread  from  entire-wheat  flour  86.2  per  cent  of  the  protein  was 
digested,  and  in  the  straight  patent  flour  bread  88.3  per  cent,  while 
96.2  per  cent  of  the  carbohydrates  in  the  entire-wheat  flour  bread  and 
97.7  per  cent  of  those  in  the  bread  from  the  straight  patent  flour  were 
found  to  be  digestible. 

An  examination  of  the  tables  also  shows  in  each  of  the  series  a  range 
of  from  4  to  nearly  6  per  cent  in  the  digestion  coefficients  of  each  of 
the  nutrients.  This  is  probably  due  to  differences  in  the  digestive 
powers  of  the  three  subjects.  Thus,  for  example,  subject  No.  3 
digested  the  bread  made  from  straight  patent  flour,  entire-wheat 
flour,  and  graham  flour  more  completely  than  either  subject  No.  1  or 
No.  2.  While  individual  differences  are  observed  in  the  three  series 
of  experiments,  in  every  case  it  appears  that  each  subject  digested 
the  nutrients  in  the  straight  patent  flour  bread  more  completely  than 
the  nutrients  in  either  the  entire- wheat  bread  or  the  graham  bread. 


30 


Hence  the  results  for  the  average  digestibility  in  the  different  scries 
of  experiments  arc  strictly  comparable. 

The  tables  also  compare  tin1  results  of  the  experiments  reported  in 
tins  bulletin  and  those  formerly  reported."  It  will  be  observed  that 
although  the  digestion  coefficients  are  somewhat  larger  in  the  experi- 
ments here  reported  than  in  those  of  ls(.*!»-l(.M>o,  there  is  a  general 
similarity  of  results.  In  both  series  the  nutrients  of  the  bread  from 
standard  patent  flour  are  the  most  and  those  of  graham  the  least 
digestible,  the  entire-wheat  flour  bread  being  between  the  two.  These 
experiments  are  regarded  as  strictly  comparable.  Considering  the 
two  years'  investigations  as  a  whole,  six  subjects  wen1  employed  and 
eighteen  separate  digestion  experiments  were  made. 

Table  1(>  gives  the  average  digestibility  of  the  nutrients  and  availa- 
bility of  the  energy  in  the  three  kinds  of  bread  as  shown  by  the  results 
of  the  two  series.  It  is  believed  that  these  figures  show,  with  a  fair 
degree  of  accuracy,  the  comparative  digestibility  of  the  protein  and 
carbohydrates  and  availability  of  energy  in  bread  made  from  the  three 
kinds  of  flour  when  milled  from  the  same  lot  of  hard  spring  wheat 
and  consumed  under  similar  conditions.  The  results,  considered  as 
a  whole,  show  that  the  protein  in  the  straight  patent  flour  bread  is 
6.i)  per  cent  more  digestible  than  that  of  the  graham  bread,  while  the 
carbohydrates  are  5.6  per  cent  more  digestible.  The  amount  of  avail- 
able energy  in  the  straight-flour  bread  is  also  greater  by  7.5  per  cent 
than  that  in  the  graham  bread. 

In  Table  17  the  total  and  digestible  protein  and  carbohydrates  and 
total  and  available  energy  in  the  three  different  kinds  of  flour  as  milled 
are  given.  These  values  for  digestible  nutrients  and  available  energy 
were  obtained  by  multiplying  the  percentage  of  total  nutrients  and 
energy  by  the  coefficients  given  in  Table  17. 


Table  17. — Percentages  <>f  digestible  protein  and  carbohydrates,  and  a callable  energy  in 
entire-wheat,  graham,  and  straight  patent  flours  as  milled. 


Protein  (Nx5.70). 


Glade  of  flour  from  hard  spring  wheat. 


Straight  patent 
Entire  wheat  .. 
(iraliam 


DibfeSti" 


Per  a  nt. 

13.60 
13.  72 
14.21 


Prr  ft  nt. 
12. 01 
11.83 
11.77 


Carbohydrates.        Energy  per  gram. 


Total. 


Per  cent. 
72.  04 
70.09 
68. 55 


Digesti- 
ble. 


Per  cent. 
70.31 
67.43 
62.  62 


Total. 


Per  cent. 
3.861 
3.877 
3.971 


Avail- 
able. 


Per  cent. 
3.510 
3.481 
3.  379 


There  was  a  somewhat  larger  amount  of  digestible  protein  in  the 
straight  patent  flour  than  in  either  the  graham  or  entire-wheat  flour. 
In  the  straight  patent  flour  there  was  70.31  per  cent  of  digestible 
carbohydrates,  in  the  entire-wheat  flour  67.43   per  cent,  and  in  the 


«U.  8.  Dept.  Agr.,  Office  of  Experiment  Stations  Bui.  101,  p.  33. 


31 

graham  flour  62.62  percent;  that  is.  the  carbohydrates  of  the  straight 
patent  flour  were  much  more  digestible  than  those  of  either  the  entire 
wheat  or  graham  Hour.  The  amount  of  available  energy  of  the  si  might 
patent'  Hour  is  also  Larger  than  that  of  either  the  graham  or  entire- 
wheat  flour. 

On  comparing  the  figures  in  this  table  with  those  previously  reported0 
it  will  be  observed  that  the  results  for  protein  here  given  are  higher. 
This  is  due  to  two  facts  already  pointed  out,  namely,  that  the  per- 
centage of  protein  in  the  wheat  employed  in  these  experiments  was 
higher,  and  the  coefficients  of  digestibility  were  larger.  The  signifi- 
cance of  the  results,  however,  is  the  same  in  both  eases.  Briefly  stated, 
the  results  of  all  of  the  experiments  with  hard  spring  wheat  show  that 
the  digestible  protein  and  carbohydrates,  as  well  as  the  amount  of 
available  energy,  are  greater  in  the  standard  patent  flour  than  in  either 
the  graham  or  entire-wheat  flour. 

No  marked  variations  in  the  balance  of  income  and  outgo  of  nitrogen 
were  observed  in  the  different  periods  except  such  as  were  due  to 
differences  in  the  amounts  consumed.  In  other  words,  judged  by  the 
data  regarding  the  metabolism  of  nitrogen,  the  three  sorts  of  breads 
served  the  body  equally  well. 

The  results  of  these  experiments  confirm  those  of  earlier  work  with 
hard-wheat  flours,  and  show  that  when  breads  made  from  straight 
patent  flour,  entire-wheat  flour,  and  graham  flour,  milled  from  the 
same  lot  of  hard  spring  wheat,  are  fed  under  uniform  experimental 
conditions  to  men,  there  is  a  larger  amount  of  digestible  protein  and 
carbohydrates  and  available  energy  in  the  patent  flour  than  in  either 
the  entire- wheat  or  graham  flour,  although  judged  by  composition  the 
graham  flour  contains  the  most  and  the  patent  flour  the  least  total 
protein.  The  greater  digestibility  of  the  protein  and  carbohydrates 
of  the  patent  flour  is  regarded  as  due  in  part  at  least  to  the  fineness 
of  division  of  the  flour  particles,  or,  in  other  words,  to  the  fact  that  a 
considerable  portion  of  the  nutrients  in  the  graham  and  entire-wheat 
flours  are  present  in  comparatively  large  particles,  which  resist  the 
action  of  the  digestive  fluids  and  so  escape  digestion.  It  has  also  been 
suggested  that  the  cell  walls  in  the  layer  of  the  grain  directly  under 
the  bran  are  more  resistant  to  digestive  juices  than  the  walls  of  cells  in 
the  interior  of  the  kernel  (see  pp.  48,  49).  Thus  while  there  is  actually 
somewhat  more  protein,  pound  for  pound,  in  graham  or  entire-wheat 
than  in  patent  flour,  the  body  obtains  less  protein  and  energy  from 
the  coarser  than  it  does  from  the  finer  flour,  and  whatever  is  gained 
in  composition  by  adding  the  bran  or  germ  is  offset  by  the  loss  in 
digestibility. 


«U.  S.  Dept.  Agr.,  Office  of  Experiment  Stations  Bui.  101,  p.  :;.",. 


32 

DETAILS  OF  THE  DIGESTION  EXPERIMENTS  WITH  BREAD  FROM 
DIFFERENT  GRADES  OF  SOFT  WINTER  WHEAT  FLOUR. 

In  order  to  determine  whether  the  results  obtained  with  oread  from 
hard-wheat  flours  would  be  the  same  with  Hours  from  wheat  of  a  dif- 
ferent character,  fifteen  digestion  experiments  were  made  with  bread 
from  graham,  entire-wheat,  and  standard  patent  flours  milled  from  soft 
winter  wheat.  The  results  of  these  experiments  are  reported  on  the 
following  pages. 

Two  sets  of  experiments  were  made.  In  one  set.  comprising  the 
first  six  of  the  following  experiments,  the  flours  used  were  prepared 
from  the  same  lot  of  Indiana  soft  winter  wheat  by  a  milling  company 
of  (  roshen,  Ind.  Only  two  kinds  of  flour  were  used  in  these  six  experi- 
ments, one  being  a  standard  patent  grade  similar  to  but  not  quite  the 
same  as  the  same  grade  of  flour  used  in  the  experiments  with  hard 
wheat:  the  other  was  a  so-called  entire-wheat  flour,  but  was  somewhat 
coarser  than  this  grade  of  flour  prepared  from  hard  wheat.  In  the 
second  set  of  experiments  three  grades  of  flours  were  used,  all  ground 
from  the  same  lot  of  Michigan  soft  winter  wheat  by  a  milling  company 
of  North  Lansing.  Mich. 

The  experiments  were  made  by  the  same  methods  as  were  followed 
in  earlier  work  with  hard-wheat  flours.  The  experiment  proper  was 
preceded  by  a  preliminary  meal  of  bread  and  milk,  charcoal  being  used 
to  mark  the  separation  of  the  feces.  The  experimental  period  con- 
tinued three  days  in  the  experiments  with  the  Indiana  flours,  and  four 
days  with  the  Michigan  flours.  The  subjects  were  young  men  in  good 
health,  designated  as  Nos.  1.  2,  and  3.  They  were  employed  at  farm 
Labor,  office,  and  university  work.  One  subject.  No.  1.  had  been 
employed  in  the  digestion  work  of  1900  and  1901  as  subject  No.  3. 
The  subjects  were  allowed  a  diet  of  bread  and  milk,  unrestricted  as  to 
amount,  the  quantities  consumed  at  each  meal  being  carefully  weighed. 
The  different  series  of  experiments  in  which  graham,  entire-wheat. 
and  straight-grade  flours  were  used  were  alike  in  all  respects  except 
as  regards  the  bread.  The  four  days'  diet  of  milk  and  graham  brea'd 
proved  to  be  rather  laxative.  It  was  observed  that  the  subjects  who 
were  employed  at  the  severest  labor  had  a  decided  preference  for  the 
bread  made  from  the  straight  and  mixed  grade  flours,  while  the  one 
employed  at  office  and  university  work  did  not  have  so  pronounced  a 
preference.      In  no  case  was  the  graham  bread  preferred. 

Tables  18  to  32  record  the  data  of  the  several  digestion  experiments. 

DIGESTION  EXPERIMENT  NO.   309. 

Kind  of  food. — Milk,  and  bread  made  from  straight-grade  flour. 
Subject. — Man  No.  1;  age.  25  years:  employed  at  office  work. 
IT  ight.     At  the  beginning  of  the  experiment.  161.25  pounds;  at 
the  close,  162  pounds. 


33 

Duration* — Three  days,  with  nine  meals,  beginning  with  breakfast 
April  9,  1902. 

Table  is. — J:, suits  of  digestion  >  vperinn  •  ! 


Bampfc  ' 
No. 

Weight 

ol 

material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

combus- 
tion. 

228 

22 1 

Pood  oonsumed: 

Bread  

Milk 

Total 

Feces  (  water  free)  

Grams. 
2,950.0 
9,850.0 

Grams. 
236.3 
826.0 

Grams. 
17.7 

431.  1 

Grams. 

1,613.9 

445.2 

<,  nuns. 

16.0 

77.8 

Calories. 

7.994 

562. 3 

419.1 

1.959.1 

92.  B 

15.677 

225 

166.0 

23.  4 

28. 3 

74.9 

39.4 

ft35 

Estimated  feces  from  food  other 

317 

Estimated       feces       from 
bread 

Total  amount  digested 

Estimated  digestible  nutrients 
in  bread 

Coefficients  of  digestibility  of 
total  food 

13.6 

6.7 

66.0 

188 

538. 9 
222.  7 

120.  8 

11.0 

1.884.2 
1.447.9 

53.4 

14,  842 

7, 506 

l'i  r  a  ut. 

Per  cent. 

95.8 

94.2 

l'i  r  c>  ut. 
93.7 

62.1 

Per  cent. 
95.6 

Per  cent. 
57.  5 

Per  cent. 
94.7 

Estimated  coefficients  of  diges- 
tibility of  bread 

93.9 

Proportion  of  energy  actually 
available  to  body: 

90.4 

In  bread  alone 

90.4 

During  this  experiment  the  subject  eliminated  6,023  grams  urine, 
containing  66.25  grams  nitrogen.  The  nitrogen  balance  per  day  was 
therefore  as  follows:  Income  in  food.  31.20  grams:  outgo  in  urine. 
22. <>S  grams,  and  in  feces,  1.25  grams,  implying  a  gain  of  7.87  grams 
nitrogen,  corresponding  to  19.2  grams  protein. 

DIGESTION  EXPERIMENT  NO.   310. 

Kind  of  food. — Milk,  and  bread  made  from  straight-grade  flour. 

Subject. — Man  No.  2:  age.  25  years:  university  student:  employed 
at  average  farm  labor  four  hours  per  day. 

Weight. — At  the  beginning  and  close  of  the  experiment.  163.75 
pounds. 

Duration. — Three  days,  with  nine  meals,  beginning  with  breakfast 
April  9,  1902. 

Table  19. — Results  of  digestion  experiment  No.  SlO. 


Sample 
No. 

Weight 

Oi          Protein, 
material. 

v,.t          Carbo-         ,  h 
Fat-      hydrates.      Ash' 

Heat  of 
combus- 
tion. 

223 

Food  consumed: 

Bread 

Grams. 
2, 860.  0 
7,850.0 

Grams. 

229. 0 

.  259.8 

Grams.      Gra    s.      Grams. 

17.2        1,467.7             14.6 

343.8          854.8            62.0 

Calories. 

224 

Milk 

6. 123 

Total 

488.8  i        361.0       1.822.5             76.6           13,874 

Feces  ( water  free) 

226 

147.0              32.1    '           23.3              57.2              34.4                  77s) 

Estimated  feces  from  food  other 
than  bread 

7.  8              17.2                7.1    ' 1               287 

Estimated     feces     from 
bread 

24.3 

6. 1            50. 1    

492 

19017— No.  126—03- 


34 


Table  L9.  —  Results  of  digestion  <  rperimeni  No.  S10 — Continued. 


Sample 
No. 


Weighl 

of         Protein, 
material. 


Fat. 


Carbo- 
hydrates. 


Ash. 


Bea1  of 
combus- 
tion. 


j 

Orams.  Grams. 

Total  amount  digested 156.  7 

Estimated  digestible  nutrients 

in  bread Jul.  7 


Qrams.       drains. 
337. 7        1 


u.o     i .  417.*; 


Grams.      Calories. 
1J.-'  13,095 


259 


Coefficients  of  digestibility  of    Percent. 

total  food 

Estimated  coefficients  of  <ii.ur*'<- 

tibility  of  bread 

Proportion  of  energy  actually 
available  to  body: 

In  total  food 

In  bread  alone 


Percent.    Percent. 

93.4 


64.4 


I'<r  cut.       I'(r  CI  lit. 

96.9  -v..  1 


l'<  /•  <■<  nt. 
94.  4 


93. 


90.3 
90.4 


During-  this  experiment  the  subject  eliminated  4:,296  grains  urine, 
containing  64.61  grams  nitrogen.  The  nitrogen  balance  per  day  was 
therefore  as  follows:  Income  in  food.  27.25  grams;  outgo  in  urine, 
21.54  grams,  and  in  feces,  1.71  grams,  implying  a  gain  of  4  grams 
nitrogen,  corresponding  to  25  grams  protein. 

DIGESTION  EXPERIMENT  NO.  311. 

Kind  of  food. — Milk,  and  bread  made  from  straight-grade  flour. 

Subject. — Man  No.  3:  21  years  of  age.  empWed  at  average  farm 
labor. 

in  ight. — At  the  beginning  of  the  experiment,  151.75  pounds:  at  the 
close,  150.5  pounds. 

Duration.. — Three  days,  with  nine  meals,  beginning  with  breakfast 
April  9,  1902. 

Table  20. — Results  of  digestion  experiment  No.  oil. 


Sample 

No. 

Weight 
of 

material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 
combus- 
tion. 

223 

Food  consumed: 

Bread  

Grams. 
2,572.0 
6,771.0 

Grams. 
206.  0 

•224.1 

Grams. 
15.4 

2%.  6 

Grams. 

1 .  319.  9 

306. 1 

Grams. 
13.1 
53.5 

6,970 

224 

Milk 

6,281 

Total 

480. 1 

312.  0 

1,626.0 

66.6 

12. 251 

Feces  (water  free  i 

227 

156.0 

41.7 
6.  7 

14.  2 

61.5 

38.6 

686 

Estimated  feces  from  food  other 
than  bread 

Estimated    feces    from 
bread 

Total  amount  digested 

55.  4 

388.  4 
171.0 

297.  8 

1.564.5 
1,264.5 

28.0 

11.. 565 

Kstimated  digestible  nutrients 
in  bread  

Coefficients  of  digestibility  of 
total  food 



Per  cent. 

Percent. 

90. 8 

83.0 

Pi  r  cent. 
95.  5 

96.  2 

P<  r  Ci  nt. 
42.0 

1 

94.4 

Estimated  coefficients  of  digest- 
ibility of  bread 

a  93. 5 

Proportion  of  energy  actually 

available  to  body: 
In  total  food... 

90.4 

o90.4 

1 

a  Calculated  according  to  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 


85 

During  this  experiment  the  subject  eliminated  1,486  grams  urine. 
containing  58.77  grama  nitrogen.  The  nitrogen  balance  per  day  was 
therefore  as  follows:  Income  in  food  24  grams;  outgo  in  urine  L9.59 
grams,  and  in  feces  223  grams,  implying  a  gain  of  2.18  grama  nitrogen, 
corresponding  to  13.6  grams  protein. 

DIGESTION  EXPERIMENT  NO.   312. 

Kind  of  food.     Milk,  and  bread  made  from  finely  ground  graham 

or  entire-wheat  Hour. 

Subject. — Man  No.  1,  as  in  experiment  No.  309. 
Weight. — At  the  beginning  of  the  experiment  163.75  pounds:  at  the 
close  164  pounds. 

Duration.  -Three  days  with  nine  meals,  beginning  with  breakfast 
April  14,  1902. 

Table  21. — Results  of  digestion  <  xpt  rum  nt  No.  812. 


Sample 
No. 

Weight 

of 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

combus- 
tion. 

231 

Food  consumed: 

Bread 

Grams. 

3,110.0 
9, 500.  0 

Grams. 

265. 3 
315.  4 

Grams. 
31.7 
W3.6 

Grams. 

1,539.1 

444.6 

Grams. 

45.  4 
73.1 

Calories. 
8,210 

2S-2 

Milk 

7,  723 

Total 

580.7 

475.3 

1,983.7 

118.5 

15, 933 

Feces  ( water  free ) 

283 

260.  3 

37.3 
9.4 

13.9 

157.  4 
8.9 

51.7 

1,130 

Estimated  feces  from  food  other 
than  bread 

Estimated    feces     from 

27.9 

148  5 

Total  amount  digested 



543.  4 
237.  4 

461.4 


1,826.3 
1,390.6 

66.8 

14, 803 

Estimated  digestible  nutrients 
in  bread  

Coefficients  of  digestibility  of 
total  food 

Per  cent. 

Per  >■>  nt. 
93.  6 

89.  5 

Per  <■>  ut. 
97.1 

Per  cent. 

92.1 

90.  3 

Per  ct  nt. 
56.  i 

Per  cent. 

Estimated  coefficients  of  digest- 
ibility of  bread   

<i90.2 

Proportion  of  energy  actually 
available  to  body: 

88.6 

a  85.2 

a  Calculated  according  to  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  5,201.7  grams  urine, 
containing  68.23  grams  nitrogen.  The  total  nitrogen  balance  per  day 
was  therefore  as  follows:  Income  in  food,  32.34  grams:  outgo  in  urine, 
22.7-i  grams,  and  in  feces,  1.95  grams,  implying  a  gain  of  7.65  grams 
nitrogen,  corresponding  to  47. S  grams  protein. 

DIGESTION  EXPERIMENT  NO.   313. 

Kind  of  food. — Milk,  and  bread  made  from  finely  ground  graham 

or  entire-wheat  flour. 

Subject. — Man  No.  2,  as  in  experiment  No.  310. 

Weight. — At  the  beginning  of  the  experiment.  164.5  pounds:  at  the 
close,  164.75  pounds. 


36 


Duration, — Three  day-,  with  nine  meals,  beginning  with  breakfast 
April  14.  1902. 

Table  22.  —  Results  of  digestion  experiment  No.  SIS. 


Sample 

No. 

Weiehl 

oi" 

material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 

combus- 
tion. 

231 

Food  consumed: 

Briad 

Grams. 

3.070.0 
9.770.0 

Grams. 
261.9 

324.4 

Grams. 

31.3 
456.3 

Grams. 

1,519.3 
457.  2 

'•nuns. 

14.8 

75.2 

Calorie*. 
8, 105 
7,943 

282 

Milk 

Total ... 

586.  3 

1S7.H 

1,976.5 

120.0 

16,048 

Feces  ( water  free ) 

234 

294.  0             49  :-t 

30.3 
22.  8 

164.6 
9.2 

49.8 

1,299 
319 

Estimated  feces  from  food  other 
t  ban  bread 

9.7 

Estimated    feces    from 

39.6 

7.5 

155.4 

980 

Total  amount  digested 

537.  0 

222.  3 

457.  3 
23.  8 

1,811.9 

1, 363. 9 

.      70.2 

14,749 

Estimated  digestible  nutrients 
in  bread 

1 ,  125 

Coefficients  of  digestibility  of 
total  food 

Per  cent. 

Percent. 

91 . »') 

P<  r  o  at. 

9:1..  8 

7'  .0 

Per  c  at. 
91.7 

Per  cent. 

5s.  5 

Per  cut. 
91.9 

Estimated  coefficients  of    di- 
gestibility of  bread 

84.9 

87.9 

Proportion  of  energy  actually 
available  to  body: 

87.7 

84.5 

During  this  experiment  the  subject  eliminated  5,201.7  grams  urine, 
containing  73.35  grams  nitrogen.  The  total  nitrogen  balance  per  day 
was  therefore  as  follows:  Income  in  food,  32.6*2  grams;  outgo  in  urine, 
24.45  grams,  and  in  feces,  2.60  grams,  implying  a  gain  of  5.57  grams 
nitrogen,  corresponding  to  34.8  grams  protein. 

DIGESTION  EXPERIMENT  NO.   314. 

Kind  of  food. — Milk,  and  bread  made  from  finely  ground  graham 
or  entire-wheat  flour. 

Subject. — Man  No.  3,  as  in  experiment  Xo.  311. 

Weight, — At  the  beginning  of  the  experiment.  150.5  pounds:  at  the 
close,  151  pounds. 

Duration. — Three  days,  with  nine  meals,  beginning  with  breakfast 
April  14,  1902. 

Table  23. — Results  of  digestion  experiment  Xo.  314- 


Sample 

No. 


231 
232 


235 


Weight 

of         Protein. 

material. 


Carbo- 
hydrates. 


Heat  of 
Ash.      j  combus- 
tion. 


Food  consumed: 

Bread 

Milk 

(i  run  is. 

2,  670.  0 
8,000.0 

G 

rams. 

227.  7 
265.  6 

Grams.    '' 

27  2 

373.  6 

Grams. 

1,321.4 

374.  4 

Grams. 

39.0 
61.6 

Calories. 

7,049 
6,504 

Total 

493.  3 

400.  8 

1.695.8 

100.6 

13.553 

Feces  ( water  free) 

275.  0 

X\  2 
8.  0 

11.9 

155.  4 
7.5    . 

52.6 


1,144 

Estimated  feces  from  too 

1  other 
f  r  o  m 

Estimated    feces 





47.2 

147.9    . 



37 


Table  23. — Results  of  digestion  experiment  Xo.  814 — Continued. 


Sninpli- 
No. 


Weight 

ol         Protein, 
material. 


Fat. 


Carbo- 
hydrates. 


Ural  0< 


Ash.       combus- 
tion. 


Total  amount  digested 

Estimated  digestible  nutrients 
in  bread 


Grams.      Grams.       Grams.      Grams.     Calories. 
188.1  388.9       1,540.  I  18.0  ,        12,  \m 


Coefficients  of  digestibility  of     Percent.    Percent.    Percent.    Percent. 

total  food ' 97.0  90.8  17. 7 

Estimated  coefficients  of  diges- 


tibility of  bread 
Proportion  of  energy  actually 
available  to  body: 

In  total  food 

In  bread  alone 


79.  3 


--   - 


Per  cent. 
91.6 


B7.5 
a  82.  9 


a  Calculated  according  to  the  assumption  that  90  per  cent  of  the  Eat  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  4,115.6  grams  urine, 
containing  60.9J  grams  nitrogen.     The  total  nitrogen  balance  per  day 

was  therefore  a>  follows:  Income  in  food,  27.48  grams;  outgo  in  urine. 
20.30  grams,  and  in  feces,  2.W  grams,  implying  a  gain  of  4.24  grams 
nitrogen,  corresponding  to  26.5  grams  protein. 

DIGESTION  EXPERIMENT  NO.  315. 

Kind  of  food. — Milk,  and  bread  made  from  straight  Hour. 
Subject. — Man  No.  I.  as  in  experiment  No.  309. 
Weight. — At  the  beginning  and  close  of  the  experiment,  106  pounds. 
Duration.— Four  days,  with  twelve  meals,  beginning  with  breakfast 
April  28.  1902. 

■Table  24. — Results  of  digestion  experiment  No.  315. 


Sample 
No. 

:  Weight 
'       ol 

material. 

Protein. 

M. 

Carbo- 
hydrates. 

Heat  of 
Ash.       combus- 
tion. 

244 
243 

Food  consumed:                              Grams. 

Bread  3,615.0 

Milk U,750.u 

Grams. 

274.4 
351.3 

Grams. 

13.7 
180.  6 

Grams. 

1,970.3 
565.  2 

Grams.     Calories. 

17.7             y.435 
90.5            B,719 

Total 

625.  7 

494.3 

2.541.5 

108.2          is, 154 

245 

Feces  i  water  free  | 132. 0 

29.  8 

,„..-, 

11.3 

11.3 

32.8                667 

Estimated  feces  from  food  other 

Bstlmatedfecesfrombread 

19.3 

16.  8 

Total  amount  rligested 

595.9 
253. 1 

4S3.  0 

2,  183.  4 

1  929  5 

75.4          17,487 

Estimated  digestible  nutrients 

Coefficients  of  digestibility  of    Percent. 
total  food 

Per  cent. 
95.  2 

93.0 

Ptr  cent. 

97.  7 

- 

69.7              96.3 

Estimated  coefficient  of  diges- 
tibility of  bread 

'         a  97. 3 

Proportion  of  energy  actually 
available  to  body: 

92.2 

In  bread  alone 

"  93. 4 

a  Calculated  according  to  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 


38 


During  this  experiment  the  subject  eliminated  7,317.4  grams  urine, 
containing  87.08  grams  nitrogen.  The  total  nitrogen  balance  per  day 
was  therefore  as  follows:  Income  in  food,  26.0:*  grams;  outgo  in  urine, 
21.77  grams,  and  in  feces.  1.1  !>  grams,  implying  a  gain  of  3.13  grams 
nitrogen,  corresponding  to  19.6  grams  protein. 

DIGESTION  EXPERIMENT  NO.   316. 

Emdqffood. — Milk,  and  bread  made  from  straight  flour. 
Subject. — Man  No.  2,  a>  in  experiment  No.  31<>. 
Weight. — At  the  beginning  and  close  of  the  experiment,  166  pounds. 
Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
April  28,  19(>2. 

Table  25. — Result*  of  digestion  experiment  No.  316. 


Sample 

No. 

Weight 
of 

material. 

Pmtein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 
combus- 
tion. 

Food  consumed : 

Bread 

Grams. 
3,  480.  0 
12,730.0 

Grams. 
264.1 
380.6 

Grams. 

13.2 

520. 6 

'Grams. 

1,902.3 

612.  3 

17.0 
98.0 

Calories. 
9,082 

9.445 

244 

243 

Milk 

Total 

Feces  ( water  free » 

644.  7 

533.8 

2.514.6 

115. 0 

18,527 

113.0 

26.1 

11.4 

14.8 

44.0 
12.3 

28.0 

583 

246 

Estimated  feces  from  food  other 
than  bread 

Estimated    feces    from 
bread 

14.7 

31.7 

618.6 

249.  4 

519.0 

2.  470.  6 
1  870.6 

87.0 

17  944 

Estimated  digestible  nutrients 
in  bread 

Coefficients  of  digestibility  of 
total  food 

Per  cent. 

Per  cent. 
95.  9 

94.  4 

Per  cent. 
97.2 

Per  cent. 
98.2 

9S.3 

Per  cent. 
75.6 

Per  cent 

96.9 

Estimated    coefficients    of   di- 
gestibility of  bread 

f»98.5 

Proportion  of  energy  actually 
available  to  body  : 
In  total  food 

92  7 

In  bread  alone 

a  95. 1 

1 

a  Calculated  according  to  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  6,556.6  grams  urine, 
containing  92.45  grams  nitrogen.  The  total  nitrogen  balance  per  day 
was  therefore  as  follows:  Income  in  food,  26.81  grams;  outgo  in  urine, 
23.11  grams,  and  in  feces.  1.05  grams,  implying  a  gain  of  2.65  grams, 
nitrogen,  corresponding  to  16.6  grams  protein. 

DIGESTION  EXPERIMENT  NO.   317. 

Kind  of  food. — Milk,  and  bread  made  from  straight  rlour, 

Subject. — Man  No.  3.  as  in  experiment  No.  311. 

Weight. — At  the  beginning  of  the  experiment.  151  pounds:  at  the 
clo$e,  150.25  pounds. 

Duration.  —  Four  days,  with  twelve  meals,  beginning  with  breakfast 
April  28,  1902. 


39 


Tablb  26. —  Results  of  digestion  i  vperimeni  No 


Sample 
No. 

Welghl 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

combus- 
tion. 

24  J 

2 13 

Food  consumed: 

Bread  

Milk 

Total 

Grams. 
3,380  0 
10,150.0 

Grams. 
252. 7 
803.6 

Grams. 

12.6 

415.  1 

Grains. 

1,820.8 

188.2 

drums. 
16.8 
78.2 

Calories. 

7   ,;i 

556. 2 

127.  7 

2, 808. 5 

94.5 

16, 222 

■J  1 7 

127.0 

32. 2 
9.  1 

19.4 

41*4 

9.8 

34.1 

681 

Estimated  feces  from  food  other 

Estimated      feces      from 

23.1 

31.6 

524. 0 
229.  6 

408.3 

2,267.1 
1,788.7 

60.4 

15, 541 

Estimated  digestible  nutrients 

Coefficients  of  digestibility  of 



Per  a  nt. 

Per  cent. 
94.2 

90.9 

Per  cent. 

95.5 

Per  cent 
98. 2 

98.2 


Per  cent. 
63.9 

Per  cent. 
95.8 

Estimated  coefficientsof  digest- 

a  97. 4 

Proportion  of  energy  actually 

available  to  body: 

91.8 

a  94. 1 

I 

"Calculated  according  to  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  4,747.0  grams  urine, 
containing  65.99  grams  nitrogen.  The  total  nitrogen  balance  per  day 
was  therefore  as  follows:  Income  in  food,  23.22  grams;  outgo  in  urine, 
1  *)./)<>  grams,  and  in  feces,  1.29  grams,  implying  a  gain  of  5.43  grams 
nitrogen,  corresponding  to  33.9  grains  protein. 

DIGESTION  EXPERIMENT  NO.   318. 

Kind  of  food. — Milk,  and  bread  made  from  entire-wheat  flour. 

Subject.  —  Man  No.  1,  as  in  experiment  No.  309. 

Weight. — At  the  beginning  of  the  experiment.  167.25  pounds;  at  the 
close,  168  pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
May  5,  1902. 


Table 


■Results  of  digestion  experiment  Xo.  318. 


Sample 
No. 

Weight 

of 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 

combus- 
tion. 

251 

Food  consumed: 

Bread 

Milk 

Grams. 

3,700.0 

12.000.0 

drum*. 
360.  0 

Grani8. 

10.0 

162.  0 

Grains. 

1,913.0 

570.0 

47.0 
87.6 

Calories. 
9,  952 

Total 


252     Feces  ( water  free  i 

Estimated  feces  froni  food  other 
than  bread 


Estimated  feces  from 
oread 


Total  amount  digested 

Estimated  digestible  nutrients 
in  bread 


668.  2 


502.0  i    2,483.0 


51.5 
10.8 


in 


616. 


486. 


161.5 
11.4 


150  1 


2,321.5 
1,762.9 


134.6 


1.231 


17,. Ml 


40 


Table  27. — Remits  of  digestion  experiment  No.  318— Continued. 


Sample 
No. 

Weight 

of 
material. 

Protein.  ,     Pat. 

Carbo- 
hydrates. 

Ash. 

Seat  of 
combus- 
tion. 

Coefficients  of  digestibility  of    Percent. 

Percent.    Percent. 

92.3              97.0 
86.  S    

Per  cent. 
98.5 

92.2 

Per  cent. 
66.  3 

Per  cent. 

Estimated  coefficients  of  digest 

"91.3 

Proportion  of  energy  actually 
available  to  body: 

In  total  food 

89  3 

a  87  9 

I 

a  Calculated  according  to  the  assumption  that  90  per  cent  of  the  Eat  in  the  bread  Is  digestible. 

During  this  experiment  the  subject  eliminated  7,889.1  grams  urine, 
containing  84.41  grams  nitrogen.  The  total  nitrogen  balance  for  four 
days  was  therefore  as  follows:  Income  in  food,  27.92  grams;  outgo  in 
urine,  21.10  grams,  and  in  feces,  2.06  grams,  implying  a  gain  of  1.70 
grams  nitrogen,  corresponding  to  29.8  grams  protein. 

DIGESTION  EXPERIMENT  NO.  319. 

Kind  of  food. — Milk,  and  bread  made  from  entire- wheat  Hour. 

Subject. — Man  No.  2,  as  in  experiment  No.  310. 

Weight. — At  the  beginning  and  close  of  the  experiment,  107.5 
pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
May  5,  1902. 

Table  28. — Results  of  digestion  experiment  Xo.  319. 


Sample 

No. 

Weight 

of 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 
combus- 
tion. 

251 

258 

Food  consumed: 

Bread 

Milk 

Total 

Feces  (water  free) 

Grams. 
3.  655. 0 
12,380.0 

Grams. 

304.5 
371.4 

Grams. 

39.5 

476.6 

Grams. 

1, 889. 5 
588.0 

Grams. 
46.4 
90.4 

Calorics. 
9.831 
9,100 

675. 9 

516.1 

2,  477.  5 

136.8 

18, 931 

253 

302.  0 

63.4 
11.1 

35.2 
23.8 

140.1 
11.8 

63.3 

1.332 

E-ti  mated  feces  from  food  other 
than  bread 

Estimated     feces     from 

351 

52.  3 

n.4 

128.  3 

981 

Total  amount  digested 

Estimated  digestible  nutrients 
in  bread 

Coefficients  of  digestibility  of 
total  food  

"Z": 

612.  5 
252.2 

480.  9 
28.1 

2.  387.  4 
1.761.2 

73.5 

17, 599 
8,850 

Per  cent. 

Per  cent. 
90.6 

82.8 

Per  cent. 
93. 2 

71.1 

Per  cent 

94.3 

93.2 

l\r  cent, 
53.7 

Per  cent 

92.9 

Estimated    coefficients  of   di- 
gestibility of  bread 



90.0 

Proportion  of  energy  actually  j 
available  to  body: 

88.9 

86.  8 

During  this  experiment  the  subject  eliminated  6,910.1  grams  urine, 
containing  101.58  grams  nitrogen.  The  total  nitrogen  balance  per  day 
was  therefore  as  follow^:  Income  in  food.  28.21  grams;  outgo  in  urine, 


41 

25.30  grams,  and  in  feces,  2.57  prams,  Implying  a  gain  of  0.25  gram 
nitrogen,  corresponding  to  1.6  grains  protein. 

DIGESTION  EXPERIMENT  NO.  320. 

Kind  <>f  food.  —  Milk,  and  bread  made  from  entire-wheat  Hour. 
Subject.  -Man  No.  3,  as  in  experiment  No.  31  1. 

Weight. — At  the  beginning  of  the  experiment,  L50  pounds;  at  the 

close,  151.5  pounds. 

Duration.  -Four  days,  with  twelve  meal-,  beginning  with  breakfast 
May  5,  1902. 

Table  29. — Results  of  digestion  exp*  rirru  ni  No.  S20. 


Sample 
No. 

Weight 

of 

material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Seal  of 
combus- 
tion. 

251 

258 

Food  consumed: 

Bread  

Milk 

Grams. 

3, 650.  0 
11,750.0 

Grams. 

304.0 
352.5 

Grams. 

39.4 
452.  4 

(i  rums. 

1,887.1 

558.1 

Grams. 

46.3 

85.8 

Calories. 

9,818 

Total 

656. 5 

491.8 

2,445.2 

132. 1 

IS,  454 

254 

262.0 

48.9 
10.6 

15.7 

135.  6 
11.2 

61.7 

1,045 

Estimated  feces  from  food  other 

Estimated      feces      from 
bread 

Total  amount  digested 

38.3 

124.  4 

607.6 
265.  7 

476.1 

2,  309.  6 
1.762.7 

70J 

17,409 

Estimated  digestible  nutrients 
in  bread 

Coefficients  of  digestibility  of 
total  food  



P<  r  a  nt. 

Pi  r  a  ut. 
92.5 

S7.4 

Per  cent. 

96.8 

Per  cent. 
94.4 

93.4 

Per  <■<  nt. 
53.3 

Per  <■<  nt. 

94.3 

Estimated    coefficients   of   di- 
gestibility of  bread 

"92.7 

Proportion  of  energy  actually 
available  to  body: 
In  total  food 

90.2 

a  89. 4 



a  Calculated  according  to  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  5,476.6  grams  urine, 
containing  88.17  grams  nitrogen.  The  total  nitrogen  balance  per  day 
was  therefore  as  follows:  Income  in  food,  27.44  grams;  outgo  in  urine. 
22.04  grams,  and  in  feces  1.96  grams,  implying  a  gain  of  3.44  grams 
nitrogen,  corresponding  to  21.5  grams  protein. 

DIGESTION  EXPERIMENT  NO.  321. 

Kind  <f  fond. — Milk,  and  bread  made  from  graham  flour. 

Subject. —  Man  No.  1,  as  in  experiment  No.  309. 

Weight. — At  the  beginning  of  the  experiment,  169.75  pounds;  at  the 
close,  170  pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
May  16,  1902. 


42 


Table  30.  —  Results  of  digestion  experiment  No.  321. 


Sample 
No. 

Weight 
material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Heat  of 
Ash.       combus- 
tion. 

•j  mi 

Pood  consumed: 

Bread 

Grains. 
U,  850.0 

Grams. 
308.9 

385. 1 

tint  ins. 

32.2 

527.  3 

drum*. 

1,891.8 

&96. 1 

a  nuns.     Calories. 
53.0           9,68] 

259 

Milk 

9L2            9,207 

Total 

694.0 

559.  5 

2,  487.  9 

144.  s          18,888 

389.0 

75.9 
1L6 

25.  1 

222. 0 
11.9 

66.1            1,641 

Estimated  feces  from  food  other 

Estimated     feces     from 

64.3 

210. 1 

618.1 
244.6 

534.4 

2. 265. 9 
1,681.7 

78.7           17,247 

Estimated  digestible  nutrients 

Coefficients  of  digestibility  of 
total  food 

l'<  r  a  at. 

Per  cent. 
89.1 

79.2 

Per  cent. 
95.5 

P<  /■  cent. 

91.1 
88.9 

P<  /■  cent, 

54.4 

Per  cent. 
91.3 

Estimated  coefficients  of  diges- 
tibility Of  bread 

a  85. 8 

Proportion  of  energy  actually 
available  to  body: 

87.2 

a  82. 7 

((Calculated  according  to  the  assumption  that  90  per  cent  of  the  fat  in  the  bread  is  digestible. 

During  this  experiment  the  subject  eliminated  5,211  grams  urine, 
containing  73. 48  grams  nitrogen.  The  total  nitrogen  balance  per  day 
was  therefore  as  follows:  Income  in  food,  28.95  grams;  outgo  in  urine, 
18.37  grams,  and  in  feces,  3.04  grams,  implying  a  gain  of  7.54  grams 
nitrogen,  corresponding  to  47.1  grams  protein. 


DIGESTION  EXPERIMENT  NO.   322. 

Kind  of  food. — Milk,  and  bread  made  from  graham  flour. 

Subject. — Man  No.  2,  as  in  experiment  No.  310. 

Weight — At  the  beginning  and  close  of  the  experiment,  166.5 
pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  break- 
fast May  16,  190&. 

Table  31. — Results  of  digestion  experiment  Xo.  322. 


Sample 
No. 

we»fh' 

material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 
combus- 
tion. 

260 

Food  consumed: 

Bread 

Grams. 
3,455.0 

11,750.0 

Grams. 
288.8 
381.9 

Grams. 

30.1 

522. 9 

Grams. 

1,  768.  9 

591.0 

Grams. 
50.1 
90.5 

Calories. 
9,052 

Milk 

9,130 

Total 

670.7 

553. 0 

2, 359. 9 

140.6 

18, 182 

Feces  (water  fr.ee) 

262 

387.0 

69.1 
11.5 

54.1 
26.1 

197.9 
11.8 

65.9 

1,730 

Estimated  feces  from  food  other 
than  bread 

361 

Estimated     feces      from 
bread 

57.6 

28.0 

186.1 

1,369 

Total  amount  digested 

601.6 
231.2 

498.  9 

2.1 

2. 162. 0 

1,582.8 

74.7 

16, 452 

Estimated  digestible  nutrients 
in  bread 

7,683 





43 


Table  31. — Results  of  digestion  experiment  No.  ■'>.'. — Continued. 


Sample 
No. 

Weigbt 

Protein, 
material. 

Km             ' 

haI-      hydrates. 

Aah. 

combus- 
tion. 

Coefficients  of  digestibility  of 
total  food ." 

Percent.    Per  cent. 

U.    Per  cent. 
90.2           91.6 

T.ii 

l'>  r  c  at. 
58.  l 

Estimated  coefficients  of  digest- 
ibility <>f  bread 



so.l 

81.7 

Proportion  of  energy  actually 
available  to  body: 

In  bread  alone 

During  this  experiment  the  subject  eliminated  4,532  grams  urine, 
containing  52.57  grams  nitrogen.     The  total  nitrogen  balance  per  day 

was  therefore  as  follows:  Income  in  food,  27.94  grams;  outgo  in  urine. 
13.14  grams,  and  in  feces.  2.7t>  grams,  implying  a  gain  of  12.04  grams 
nitrogen,  corresponding  to  75.2  grams  protein. 

DIGESTION  EXPERIMENT  NO.  323. 

Kind  of  food. — Milk,  and  bread  made  from  graham  flour. 

Subject — Man  No.  3,  as  in  experiment  No.  311. 

Weight. — At  the  beginning  of  the  experiment.  151.25  pounds;  at 
the  close,  150.5  pounds. 

Duration. — Four  days,  with  twelve  meals,  beginning  with  breakfast 
May  16,  1902. 


Table  32. — Results  of  digestion  experiment  No.  828. 


Sample 
No. 

Weight 
of 

material. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Ash. 

Heat  of 
combus- 
tion. 

260 
259 

Food  consumed: 

Bread 

Milk 

Total 

Grams. 

3,  580.  o 

11.000.0 

Qrams. 
299. :; 

:>5,.  ■"> 

Grams. 
31.1 
189.5 

Grams. 

1,832.9 

553. 3 

Grams. 
51.9 
84.7 

Calories. 

9.  379 
8,540 

G56. 8 

520.  6 

2.  3.N5.  2 

i3ti.  t; 

17.92") 

26S     Feces  ( water  free  | 

Estimated  feces  from  food  other 
than  bread 


384.0 


73.4 

10.  7 


31.7 
24.5 


202.  3 

11.1 


1,001 
348 


Estimated      feee- 
bread 


from 


191.2 


Total  amount  digested 

Estimated  digestible  nutrients 
in  bread  


Coefficients  of  digestibility  of 
total  food 

Estimated  coefficients  of  diges- 
tibility of  bread 

Proportion  of  energy  actually 
available  to  body: 

In  total  food 

In  bread  alone 


583.  I 


188.9 


2.1->3.9 
1,041.7 


00.  0  10, 324 
8,126 


t.    Percent.    Per  cent.    Percent.    !■ 

91.5  91.1 

79.0  


87.0 
83.  5 


During  this  experiment  the  subject  eliminated  4,509  grams  urine, 
containing  85.16  grams  nitrogen.  The  total  nitrogen  balance  per  day 
was  therefore    as  follows:   Income   in  food.   27.42  grams:    outo-o  in 


44 

urine,  21.29  grams,  and  in  feces.  2.94  grams,  implying  a  gain  of  3.19 
grams  nitrogen,  corresponding  to  19.9  grams  protein. 

SUMMARY  OF  RESULTS  OBTAINED  WITH   SOFT  WINTER  WHEAT 

PRODUCTS. 

In  Table  33  a  summary  is  given  of  the  digestibility  of  the  nutrients 
and  availablity  of  the  energy  of  the  entire  food  of  the  various  digestion 
experiments  with  milk  and  white  bread  from  mixed-grade  Hour,  white 
I  tread  from  straight-grade  Hour,  entire-wheat  bread,  and  graham,  aJl 
ground  from  soft  winter  wheat. 

Table  33, — Summary  of  digestion  experiments  with  soft   winter  wheat;    digestibility  of 
nutrients  and  avauabUity  of  em  rgy  of  total  food. 


Experi- 
ment 
No. 

Subject 

Kind  of  food. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Energy. 

309 

310 

l 
2 
3 

1 
2 
3 

1 
2 
3 

1 
2 
3 

1 
2 

3 

Experiments  with  Indiana  wheat: 

Milk  and  white  bread  (mixed  grade  i . . . 
do 

Per  cent. 
95.  8 

93.4 
90.3 

Per  <■'  at. 
93.  7 
93.  5 
95.  * 

Pi  r  ''nt. 
96.2 
96.9 
96.  2 

/"'/•  cent 
90.4 
90.3 

311 

....do 

9('.4 

93.  2 

94.2 

90.4 

90  4 

Milk  and  entire-wheat  bread 

....do 

....do 

Average  of  3 

Experiments  with  Michigan  wheat: 

Milk  and  white  bread  (standard  patent  i 

do 

....do 

Average  of  3  . .   

312 
313 
314 

93.  6 
91.6 

88.8 

97.1 
93.8 
97.0 

92.1 
91.7 

90.  8 

So.  6 

ST.  7 
87.5 

91.3 

90.0 

91.5 

^7.9 

315 
316 
317 

95.2 
95.9 

94.  2 

97.7 
97.2 
95.  5 

97.7 
98.  2 
98.  2 

92.2 

92.7 
9-1.8 

95.1 

90.8 

98.  0 

92.2 

Milk  and  entire-wheat  bread 

318 

92.3 
90.0 
92.  5 

97.0 
93.2 
96.8 

93.  5 
94.3 

94.  4 

S9.3 

319 
320 

--..do 

....do .* 

Average  of  3 

90.2 

91.8 

95.7 

94.1 

89.  5 

Milk  and  graham  bread 

321 

89.1 
89.  7 
88.8 

95.  5 
90.2 
93.9 

91.1 

91.6 
91.5 

87.  2 

322 
323 

....do 

....do 

SO.  2 
87.0 

Average  of  3 

89.2 

93.2 

91.4 

86.8 

The  results  summarized  in  the  table  show  that,  in  general,  the  ration 
consisting  of  milk  and  white  bread  made  from  the  patent  grade  flour 
was  more  digestible  than  the  rations  of  milk  and  bread  made  from 
either  of  the  other  kinds  of  flour,  also  that  a  larger  percentage  of 
energy  was  available  to  the  body  in  the  case  of  white  bread  and  milk 
than  from  the  entire-wheat  or  graham  bread  and  milk. 

In  the  experiments  with  Indiana  soft  wheat  individual  differences  a^ 
regards  the  ability  to  digest  the  bread  and  milk  rations  were  quite 
pronounced  with  the  various  subjects;  in  the  ease  of  the  white  bread,  a 
difference  of  about  5.5  per  cent  in  the  digestibility  of  the  protein  being- 
observed.  Subject  No.  1  digested  the  wheat  bread  and  also  the  entire- 
wheat  bread  more  completely  than  did  subject  No.  2  or  2s o.  3.     With 


45 

each  subject,  however,  the  digestibility  of  the  ration  with  white  bread 
was  greater  than  that  with  entire  wheat.  In  the  experiments  with 
Michigan  soft  wheat  individual  differences  are  noticeable,  but  they 
arc  less  pronounced,  and,  as  was  the  case  with  the  other  wheats,  each 
subject  digested  the  ration  of  white  bread  and  milk  more  completely 
than  bread  made  from  either  of  the  other  flours. 

In  Table  34  the  calculated  digestibility  of  the  nutrients  and  availa- 
bility of  the  energy  of  the  bread  alone  are  given: 

Table  .'54. — Summary  of  di</rsti<>,i  experiment*  with  soft  winter  wheat;   digestibility  of 
nutrients  end  availability  of  energy  of  bread  (done. 


Experi- 
ment 
No. 

Subject 

309 

l 

310 

2 

311 

3 

312 

1 

313 

2 

314 

3 

315 

1 

310 

2 

317 

3 

318 

1 

319 

■1 

320 

3  1 

321 

1 

322 

2 

323 

3 

Kind  of  food. 


Experiments  with  Indiana  wheat: 
White  bread  (mixed  grade  noun 

....do 

....do 


Average  of  3.. 

Entire-wheat  bread 

....do 

....do 


Average  of  3. 


Experiments  with  Miehigan  wheat: 
White  bread  (standard  patent). 

do 

....do 


Average  of  3.. 

En  tire- wheat  bread 

....do 

....do.../ 


Average  of  3. 


Graham  bread. 

....do 

....do 


Average  of  3. 


**>**»■  b$$eV    **»•* 


1>,  r  n  nt. 
94.2 
89.4 
83.0 


I'll-  VI  lit.        I'n- CI  lit. 

95.6  90.4 

96.6  '  90.4 

95.8  i  90.4 


88.9 

96.0  ; 

90.4 

89.5 
84.9 
79.3 

90.3 

v.*.  8 

■     88. 8 

85. 2 
84.  5 
82.9 

84.6 

89.6 

84.2 

93.0 
94.4 
90.9 

97.6 
98.3 

98,  -1 

93.4 
95.1 
94.1 

92.8 

98. 0 

94.2 

86.8 
82.8 
87.4 

92.  2 
93. 2 
93.4 

s:.  9 

86.8 
89.4 

85.7 

92.9 

88.0 

79.2 
80.1 
79.0 

88.9 

89.5  1 

89.6  : 

82.  7 
81.7 
S 

82. 6 


These  results  are  calculated,  as  explained  on  page  1H.  by  assuming 
that  97  per  cent  of  the  protein  and  98  per  cent  of  the  carbohydrates  of 
the  milk  were  digested." 

The  average  result  of  the  experiments  with  flour  milled  from  Indi- 
ana soft  winter  wheat  shows  that  S8.9  per  cent  of  the  protein  and  :♦♦; 
per  cent  of  the  carbohydrates  of  the  white  bread  from  mixed-grade 
flour  were  digested,  and  that  90.4- per  cent  of  the  energy  was  available. 
As  regards  the  bread  from  entire-wheat  flour,  ground  from  the  same 
lot  of  wheat,  S±.t)  per  cent  of  the  protein  and  89.6  per  cent  of  the  car- 


alt  was  also  assumed  that  95  per  cent  of  the  fat  of  the  milk  would  be. digested,  but 
with  this  factor  the  digestibility  of  the  fat  of  bread  could  be  computed  satisfactorily 
in  only  a  few  cases;  therefore  figures  for  this  constituent  are  left  out  of  Table  34. 
In  all  cases  where  the  digestibility  of  bread  fat  could  not  be  computed  it  was  assumed, 
in  order  to  estimate  the  available  energy  of  the  bread,  that  90  per  cent  would  be 
digested. 


46 

bohydrates  were  found  to  be  digestible,  and  84.2  per  cent  of  the  energy 
to  be  available.  It  will  be  observed,  further,  that  with  each  of  the  sub- 
jects the  nutrients  of  the  white  bread  were  more  digestible  and  the 
energy  more  available  than  was  the  case  with  the  entire- wheat  bread. 

The  white  bread  made  from  straight-grade  flour  milled  from  Michi- 
gan soft  winter  wheat  had  the  highest  digestibility  of  any  of  the  sam- 
ples ground  from  this  variety,  namely.  92.8  per  cent  of  the  protein 
and  98  per  cent  of  the  carbohydrates,  while  94.2  per  cent  of  the  energy 
was  available  to  the  body.  Of  the  protein  of  bread  from  the  entire- 
wheat  flour  milled  from  the  same  lot  of  wheat.  85.7  per  cent,  and  of 
the  carbohydrates  92.9  per  cent  were  digestible.  88  per  cent  of  the 
energy  being  available  to  the  body.  The  lowest  coefficients  of  digesti- 
bility were  found  in  the  graham  bread,  the  values  being  79.4  per  cent 
for  the  protein.  89.3  per  cent  for  the  carbohydrates,  and  82.6  per  cent 
for  the  energy  available  to  the  body.  As  will  be  seen,  there  was  a  dif- 
ference of  13.4  per  cent  in  the  average  digestibility  of  the  protein  of 
the  graham  bread  and  white  bread  made  of  flour  from  the  same  lot 
of  wheat,  while  8.7  per  cent  less  of  the  carbohydrates  of  the  graham 
bread  was  digestible,  and  11.6  per  cent  less  of  the  energy  was  avail- 
able. As  in  the  case  of  the  entire  ration,  differences  attributable  to 
individuality  are  noticeable,  which  are,  however,  not  great  enough  to 
invalidate  the  general  deduction  that  white  bread  is  the  most  digesti- 
ble, graham  bread  the  least,  and  entire-wheat  bread  intermediate 
between  them. 

Table  35  gives  a  summary  of  the  experiments  on  the  basis  of  the  pro- 
portion of  total  and  digestible  nutrients  and  available  energy  in  the 
different  grades  of  flour  as  milled  from  soft  winter  wheat: 

Table  35. — Proportion  of  total  and  digestible  nutrients  and  available  energy  in  different 

grades  of  soft  winter-wheat  flour  as  milled. 


Num- 
ber of 
sample. 


Grade  of  flour. 


221  Mixed-srrade  flour . . 

219  Entire-wheat  flour  . 

24Q  Straight  white  flour 

211  Entire-whea; 

242  Graham  flour 


Protein. 


Gar  bohydrates. 


Total         Digest-       T      ,         Digest- 
lotaL         ible.  lotal-         ible. 


Per  cent. 

Per  cent. 

Per  cent. 

12.  30 

10.93 

75.91 

12.80 

10.  -2 

71.10 

10.92 

10.13 

77. 15 

12.  01 

10. 29 

74.17 

12.  21 

9.72 

73. 27 

Per  cent. 
72.90 
00.66 
75.  61 

S  - 

65.  43 


Heat  of  combus- 
tion per  gram. 


Total. 


Avail- 
able. 


Calories. 
4.010 
4. 020 
3.799 

3.906 


Calories. 
3.645 
3.384 
3. 579 
3.  399 
3.  226 


The  digestible  nutrients  were  obtained  by  multiplying  the  percent- 
age of  the  total  nutrients  by  the  average  digestion  coefficients  given 
in  Table  34.  The  mixed-grade  flour,  for  example,  contained  12.3  per 
cent  total  protein,  which  was  found  to  be  88. 9  per  cent  digestible, 
being  therefore  equivalent  to  10.93  per  cent  of  digestible  protein. 
The  mixed-grade  flour  prepared  from  the  Indiana  wheat  contained 
10.93  per  cent   digestible  protein,   72.90  per   cent  digestible  carbo- 


47 

hydrates,  and  1  gram  of  the  Hour  yielded  3.645  calories  of  available 
energy.  The  entire-wheat  flour  prepared  from  the  same  wheal  yielded 
10.82  per  cent  digestible  'protein.  66.87  per  cent  digestible  carbo- 
hydrates, and  3.375  available  calories  per  gram.  The  difference  in 
digestible  protein  is  small,  being  0.11  percent  in  favor  of  the  mixed- 
grade  flour.  The  difference  in  the  digestible  carbohydrates  Is  quite 
large,  being  6.24  per  cent  in  favor  of  the  mixed-grade  flour.  The 
difference  in  the  available  energy  is  also  large,  amounting  to  0.26] 
caloric  per  gram  in  favor  of  the  white  Hour. 

While  there  ts  no  material  difference  as  to  the  amount  of  digestible 
protein  in  the  two  kinds  of  Hour,  the  differences  in  digestible  carbo- 
hydrates and  available  energy  are  decidedly  in  favor  of  the  mixed-grade 
flour.  The  entire-wheat  flour  contained  a  larger  amount  of  protein. 
but,  as  shown  in  Table  34,  this  protein  is  less  digestible  than  that  of 
the  mixed-grade  flour,  which  was  more  finely  granulated. 

The  straight-grade  flour  prepared  from  the  Michigan  wheat  con- 
tained 10.13  per  cent  digestible  protein,  75.61  per  cent  digestible 
carbohydrates,  and  3.574  calories  of  available  energy  per  gram.  Com- 
pared with  graham  flour,  this  shows  0A  per  cent  of  digestible  protein, 
10.18  per  cent  of  digestible  carbohydrates,  and  0.353  calorie  of  avail- 
able energy  per  gram  in  favor  of  the  white  flour.  Compared  with 
the  entire-wheat  flour,  the  results  show  a  difference  of  6.81  per  cent 
digestible  carbohydrates  and  0.180  available  energy  per  gram  in  favor 
of  the  straight-grade  flour;  the  difference  in  digestible  protein,  though 
too  small  to  be  of  significance,  is  0.16  per  cent  in  favor  of  the  entire- 
wheat  flour.  In  the  description  of  the  samples  it  was  stated  that  the 
straight-grade  flour  did  not  contain  all  of  the  granular  middlings 
which  are  usually  included  in  the  preparation  of  ordinary  straight 
flours.  Had  the  flour  contained  the  granular  middlings,  the  percent- 
age of  protein,  it  seems  fair  to  conclude,  would  have  been  higher  than 
10.92.  While  the  difference  in  total  protein  is  1.1  per  cent  in  favor  of 
the  entire-wheat  flour,  the  higher  degree  of  digestibility  of  this  con- 
stituent in  the  straight-grade  flour  makes  the  figures  for  the  total 
digestible  protein  in  the  two  kinds  of  flour  practically  the  same. 
Hence,  what  is  gained  from  the  somewhat  larger  amount  of  protein  in 
the  entire-wheat  and  graham  flours  is  lost  in  digestibility.  While  the 
difference  between  the  digestible  protein  in  the  straight-grade  and 
entire-wheat  flours  prepared  from  the  same  lot  of  soft  wheat  is  small, 
the  difference  in  digestible  carbohydrates  is  large,  being  6.8  per  cent 
in  favor  of  the  white  flour.  Since  a  larger  amount  of  digestible  carbo- 
hydrates and  available  energy  is  secured  from  the  mixed  and  straight- 
grade  flours  than  from  the  entire-wheat  flour  and  no  appreciable 
differences  were  observed  as  to  digestible  protein,  it  would  appear 
that  a  larger  total  amount  of  nutrients  and  energy  is  available  to  the 


48 

body  from  the  straight  than  from  the  entire-wheat  or  graham  flours, 

a  conclusion  in  accord  with  the  results  of  all  our  former  work. 

That  the  lower  degree  of  digestibility  of  the  entire-wheat  and  graham 
flours  was  probably  due  at  least  in  part  to  a  coarser  granulation 
of  the  particles,  which  consequently  exposed  a  relatively  smaller 
amount  of  surface  to  the  action  of  the  digestive  fluids,  was  shown  by  a 
microscopical  examination  of  the  feces.  The  feces  from  both  the 
entire-wheat  and  the  graham  flours  under  the  microscope  showed  a 
larger  proportion  of  starch  particles  that  had  not  been  acted  upon  in 
the  digestive  tract  than  the  feces  from  standard  patent  flour.  The 
micro-photographs  reproduced  (Pis.  I— III)  show  the  fineness  of  division 
of  the  three  sorts  of  flour  and  the  starch  granules  in  the  feces  obtained 
from  the  standard  patent,  the  entire-wheat,  and  the  graham  flours, 
prepared  by  grinding  in  a  mortar. 

These  deductions  are  in  accord  with  the  results  of  numerous  micro- 
scopical studies  of  the  feces  from  different  sorts  of  wheat  products,  and 
in  this  connection  it  is  interesting  to  refer  to  some  of  these  and  closely 
related  investigations.  Among  others  may  be  mentioned  the  work  of 
Runner/'  Pappenheim/  Constantinidi, *  and  Raudnitz.  d 

In  general  it  may  be  said  that  these  investigators  found  that  starch 
was  very  thoroughly  digested,  but  that  the  cells  making  up  the  outer 
portion  of  the  wheat  berry  were  little  attacked  by  the  digestive  juices, 
and  hence  the  contents  of  such  cells  were  not  assimilated.  Rubner 
pointed  out  that  the  amount  of  undigested  nitrogen  increased  with  an 
increase  in  the  amount  of  the  outer  portion  of  the  grain  retained  in 
flour  in  milling.  Rathay^  reports  experimental  studies,  of  which  he 
himself  was  the  subject,  in  which  the  diet  for  a  week  consisted  of 
graham  bread  and  tea.  The  bread  was  made  without  leaven  or  yeast. 
The  feces  from  the  fifth  and  seventh  day  were  examined  microscop- 
ically. He  found  that  the  grain  portions  which  had  been  little  masti- 
cated were  softened,  but  almost  entirely  undigested.  From  only  a 
few  of  the  outer  cells  of  the  endosperm  had  the  starch  grains  and  the 
proteid  materials  disappeared,  while  the  greater  part  of  these  nutri- 
ents was  excreted  unchanged.  The  general  conclusion  from  his  inves- 
tigations  was  that  the  greater  portion  of  the  feces  consisted  of  undi- 
gested residues  of  wheat  bran  in  the  form  of  large  flakes  composed 
of  the  seed  coats  and  aleurone  layer.  The  latter  leaves  the  intestines 
unchanged,  probably  because  the  thick  walls  of  the  aleurone  cells  pre- 
vent the  action  of  digestive  juices  upon  the  cell  contents.  So  far  as 
can  be  learned,  this  investigation  was  the  first  which  at  all  satisfac- 
_ — i , _ _ — — — — 

"Zt^chr.  Biol.,  15  (1879),  p.  115. 

i'  Lehrbucfa  der  Mi'illerei  (1890),  3d  ed.,  cited  by  Moeller. 

^Ztschr.  Biol.,  23  (1887).  p.  447. 

</Prag.  ined.  Wchnschr.,  7  (1892),  pp.  1,  13. 

eJahresber.  K.  K.  Realschule  Sechshaus,  Wien,  1874,  cited  bv  Moeller. 


U.  S.  Dept.  of  Agr.,  Bui.  1  26,  Office  of  Expt  Stations. 


Plate  I. 


i'x:*  v 


•'♦v\  "*« 


FiG.    1 


■Flour  Particles  from  Straight  Patent  Flour  No.  240  (Magnified  15 
Diameters). 


Fig.  2. 


■Flour  Particles  from  Entire-wheat  Flour  No.  241  (Magnified  15 
Diameters). 


U.  S.  Dept.  of  Agr.,  Bui.  126,  Office  of  Expt.  Stations. 


Plate  II. 


Fig.  1.— Flour  Particles  from  Graham  Flour  No.  243  (Magnified  15  Diameters). 


Fig.  2.— Feces  from  Bread  Made  from  Straight  Patent  Flour  i  Magnified  15 

diameters'. 


U.  S.  Dept.  of  Agr.,  Bui.  126   Office  of  Expt.  Stations 


Plate  III. 


* 


sr4 

A 


Fiq.  1.— Feces  from  Bread  Made  from  Graham  Flour  (Magnified  15  Diameters). 


Fig.  2.— Feces  from  Bread  Made  from  Entire-wheat  Flour  (Magnified  15 

diameters). 


49 
torily  opposed  Liebig's  idea  of  the  high  value  of  the  gluten  layer  of 

wheat. 

Perhaps  the  mo6t  extended  study  of  vegetable  residues  occurring 

in  feces  was  made  by  Moeller".  In  some  of  the  experiments  the 
diet  consisted  of  coarse  bread  with  butter  and  cheese;  white  bread, 

rice,  and  butter:  bread,  and  porridge  made  of  wheal  grits  and  milk; 
bread,  and  porridge  made  from  milk  and  flour:  oat  preparations, 
namely,  oat  grits,  oat  flake,  soup, and  oat  cocoa;  rye  bread  and  various 

mixed  diets,  or  diets  in  which  potatoes  or  Legumes  predominated. 
Portions  of  feces  were  repeatedly  washed  with  water  and  then  exam- 
ined under  the  microscope.  The  conclusion  was  reached  that  healthy 
individuals  digested  the  starch  of  cereals  and  potatoes  almost  completely, 
even  when  the  starchy  foods  were  not  in  favorable  mechanical  condition, 
as  is  the  case  in  bran  from  cereals,  in  rice,  or  in  sliced  potatoes;  and  fur- 
ther, that  the  soft  cell  walls  of  the  starch  cells  are  also  digested.  The 
aleurone  layer  of  cereals  in  which  the  cell  membranes  consist  of  pure 
cellulose  w^as  not  digested,  nor  were  the  protein  and  fat  which  form 
the  contents  of  the  cells  digested  unless  the  cell  walls  had  been  mechan- 
ically ruptured.  The  cells  making  up  the  germ  were  not  digested  or 
ruptured  by  the  action  of  the  digestive  juices.  The  author  believes 
that  these  experiments  warrant  the  conclusion  that  tine  flour  is  prefer- 
able to  coarse  flour.  Comparative  experiments  with  coarse  flour  and 
the  same  flour  after  passing  through  the  intestinal  tract,  lead  the 
author  to  the  conclusion  that  the  cell  walls  almost  absolutely  shield 
the  cell  contents  of  the  aleurone  layer  from  the  action  of  the  digestive 
juices,  and  he  concludes  that  cereal  brans  should  be  regarded  as  indi- 
gestible. The  outer  layer  of  the  cereal  grains,  including  endosperm 
cells  with  their  starch  content,  was  also  found  to  be  undigested. 

Laboratory  experiments  indicated  that  cellulose  which  had  not  ligni- 
ried  was  little  attacked  by  digestive  juices,  the  amount  being  inversely 
proportional  to  the  thickness  of  the  cell  membrane.  On  the  other 
hand,  the  middle  lamelhe  were  readily  disintegrated  by  digestive  juice-. 
Tests  with  laboratory  reagents  also  showed  that  the  inner  side  of  the 
gluten  cells  was  most  resistant  but  after  a  time  softened,  and  this  indi- 
cates that  possibly  gluten  cells  may  become  softened  in  the  intestine 
and  then  digested.  That  this  occurs  very  seldom  is  indicated  by  the 
large  number  of  unchanged  cells  found  in  the  feces. 

As  noted  above,  in  connection  with  the  experiment-  reported  in 
this  bulletin,  a  microscopical  examination  of  the  fee.-  showed  that 
in  those  from  the  graham  and  entire-wheat  breads  made  from  flour 
ground  from  the  same  lot  of  soft  wheat,  a  much  larger  number  of 
unaltered  starch  granules  were  present,  and  the  particle-  had  not  been 
as  completely  acted  upon  by  the  digestive  fluids  as  in  the  case  of  the 
straight-grade-ilour  bread. 

"Ztsehr.  Biol.,  35  (1897),  p.  291. 
19047— No.  126—03 1 


50 

Summarizing  briefly  the  results  of  the  fifteen  experiments  with  soft- 
wheat  Hour-,  it  appears  that  while  the  graham  and  entire-wheat  flours 
contain  a  larger  amount  of  protein  and  energy,  the  lower  degree  of 
digestibility  of  these  flours,  due  to  the  coarser  granulation,  renders 

available  to  the  body  a  smaller  proportion  of  total  nutrients  as  well  as 
energy  than  in  the  ease  of  straight-grade  flours,  ground  from  the  same 
wheat,  which  are  more  finely  granulated  and  more  completely  digested. 
This  is  entirely  in  accord  with  the  results  obtained  in  the  investiga- 
tions with  hard- wheat  flours  more  exhaustively  milled. 

A-  was  the  case  in  the  tests  with  bread  from  different  grades  of  hard- 
wheat  flour,  no  variations  were  observed  in  the  metabolism  of  nitrogen 
which  could  be  attributed  to  the  use  of  the  different  sorts  of  flour 
constituting  the  principal  part  of  the  diet. 

GENERAL  SUMMARY  OF  RESULTS  AND  CONCLUSIONS. 

The  experiments  with  hard  wheat  milling  products  reported  in  the 
present  bulletin  are  the  latest  of  a  fairly  extended  series  which  has 
given  uniform  results.  The  experiments  with  soft  wheat  are  the  first 
of  a  proposed  series  and  are  less  numerous  than  those  made  with  hard 
wheat.  The  results  already  obtained,  however,  are  in  accord  with 
what  has  been  learned  regarding  the  milling  products  of  hard  wheat. 
Some  general  deductions  from  the  experiments  as  a  whole  seem 
warranted. 

As  shown  by  analysis  the  patent  flour,  ground  from  the  hard  and 
soft  wheats  studied,  had  a  somewhat  lower  protein  content  than  the 
graham  flour  and  entire-wheat  flour  ground  from  the  same  wheats,  but 
according  to  the  results  of  digestion  experiments  with  the  different 
grades  of  flour  from  these  wheats,  the  proportion  of  digestible  pro- 
tein and  the  available  energy  in  the  patent  flour  was  larger  than  in 
the  coarser  grades.  The  lower  digestibility  of  the  protein  in  the  latter 
is,  it  appears,  due  to  the  fact  that  in  these  grades  a  considerable  por- 
tion of  this  constituent  is  contained  in  the  coarser  particles  (bran)  and 
thus  escapes  digestion  as  it  is  not  acted  upon  by  the  digestive  juices. 
Thus,  while  there  may  be  actually  more  protein  in  a  given  amount  of 
graham  or  entire-wheat  flour  than  in  an  equal  amount  of  patent  flour 
ground  from  the  same  wheat,  the  body  secures  less  of  the  protein  and 
energy  from  the  coarse  flour  than  it  does  from  the  tine,  since  although 
the  retention  of  the  bran  and  germ  increases  the  percentage  of  pro- 
tein it  decreases  the  digestibility.  By  digestibility  is  meant  the  dif- 
ference between  the  amounts  of  the  several  nutrients  consumed  and 
the  amounts  excreted  in  the  feces.  No  attempt  was  made  to  study  the 
ease  or  rapidity  of  digestion  of  the  different  sorts  of  flour.  When  the 
digestibility  of  different  grades  of  patent  flour  was  studied  it  was 
found  that  there  was  no  marked  difference  between  standard  patent 


51 

flour  and  the  other  grades  io  this  respect  The  digestibility  of  all 
these  do ura  was  found  to  be  high,  apparently  owing  largely  to  their 
mechanical  condition,  that  Is,  owing  to  the  tact  thai  they  were  finely 
ground. 

Microscopical  studies  of  the  feces  from  bread  made  from  the  different 
grades  of  Hour  indicate  thai  the  superior  digestibility  of  patent-flour 
bread  is  due  to  the  fineness  of  division  of  the  flour  particles  and  also  to 
the  fact  that  the  cell  walls  of  the  material  making  up  the  interior  of 
tla1  wheat  berry  are  less  resistant  to  digestive  juices  than  the  walls  of 
the  cells  making  up  the  outer  layers  of  the  grain.  In  other  words,  the 
patent  Hour  is  superior  as  regards  digestibility,  on  account  of  both  its 
mechanical  condition  and  its  physical  properties. 

In  discussions  of  the  comparative  value  of  fine  wheat  flour  and  the 
coarser  grades,  it  i>  often  claimed  that  the  larger  proportion  of  mineral 
matter,  and  especially  phosphorous  compounds,  in  whole-wheat  and 
graham  flours  is  a  reason  for  preferring  them  to  patent  flour.  In  this 
case  also  it  is  undoubtedly  true  that  the  proportion  of  mineral  con- 
stituents which  is  digestible,  or.  in  other  words,  which  the  body  can 
retain,  from  the  different  sorts  of  flour,  must  be  considered,  as 
well  as  the  amounts  which  chemical  analysis  shows  to  be  present  in 
the  food.  In  view  of  the  fact  that  there  is  apparently  no  satisfac- 
tory method  for  determining  the  proportion  of  ash  in  the  feces, 
derived  from  metabolic  products,  and  that  it  is,  therefore,  impossible 
by  present  methods  to  determine  the  true  digestibility  of  the  mineral 
constituents,  no  values  for  the  digestibility  of  ash  have  been  included 
in  the  present  bulletin.  It  may  be  noted  in  this  connection  that 
it  is  a  well- recognized  fact  that  when  the  coarser  milling  products 
are  fed  to  cattle  no  great  amount  of  phosphorus  (one  of  the  most 
important  manurial  elements)  is  retained  in  the  animal  body.  This  may 
possibly  be  an  indication  that  the  phosphorus,  even  if  present  in  con- 
siderable amounts  in  the  feed,  is  not  in  a  form  which  can  be  assimilated 
by  animals.  This  is,  however,  little  more  than  conjecture,  and  more 
experiments  with  man  and  the  lower  animals  are  needed  before  satis- 
factory conclusions  can  be  drawn. 

Briefly  stated,  the  most  important  deductions  from  the  results  of 
these  investigations  with  hard  and  soft  wheat  are  in  accord  with  the 
conclusions  drawn  from  the  earlier  investigations  of  this  series.  The 
nutritive  value  of  flour,  in  so  far  as  the  quantities  of  digestible  protein, 
fats,  and  carbohydrates,  and  available  energy  are  concerned,  is  not 
increased  by  milling  the  wheat  in  such  a  way  as  to  retain  a  large  pro- 
portion of  bran  and  germ.  The  differences  in  the  amounts  of  total 
nutrients  furnished  the  body  by  the  various  grades  of  flour  are,  how- 
ever, relatively  small,  all  grades  being  quite  thoroughly  digested. 
The  coarser  flours  have  a  tendency  to  increase  peristaltic  action,  and 
are  on  this  account  especially  valuable  for  some  persons.     Judged  by 


52 

composition  and  digestibility,  all  the  flours  arc  very  nutritious  foods, 
which  experience  has  shown  are  wholesome  as  well.  When  also  the 
fact  is  taken  into  account  that  they  furnish  nutritive  material  in  an 
economical  form,  their  importance  is  evident.  The  fact  must  not  be 
lost  sight  of  that  using  different  grades  of  flour  for  bread  making  and 
other  household  purposes  offers  B  convenient  method  of  adding  to  the 
variety  of  the  daily  diet,  a  matter  which  is  of  undoubted  importance. 


LIST  OF  PUBLICATIONS  OF  THE   OFFICE  OF  EXPERIMENT  STATIONS  ON 
THE  FOOD  AND  NUTRITION  OF  MAN-  Cdntitiued, 

Hul.    75.  Dietarj  Studies  of  University  Hunt  Crews*    Hy  u.  <  >.  Atwater  and  A.  P.  Bryant.    Pp.  72. 

Price,  5  Ants. 
Hul.    M.  Nutrition  Investigations  at  the  California  Agricultural  Experiment  Station,  ISM  L89f 

M.  E.  Jaffa.     Pp.  89.    Price,  5  cent-. 
Hul.    35.  A  Report  of  Investigations  on  the  Digestibility  and  Nutritive  Value  of  Bread.     Bj  <     i> 

Woods  and  L.  H.  Merrill.    Pp.  51.    Price,  r>  cents. 
Hul.    89.  Experiments  on  the  Effect  ol  Muscular  Work  apon  tin-  Digestibility  of  Pood  and  tip-  Metab 

oiisui  of  Nitrogen.    Conducted  at  the  Universit}   of  Tennessee,  iv,.'T  L899.    Bj  C.  E.  Wait 

Pp.  77.     Trice.  5  cents. 
Hul.    91.  Nutrition  investigations  at. the  University  of  Illinois,  North  Dakota  Agricultural  College, 

and  Lake  Brie  College,  Ohio,  1895-1900.    Hy  H.  s.  <  Irindley  mid  .1.  L.  Sajnmis,  B.  P.  Ladd, 

and  Isabel  Hevierand  Elizabeth  C  sprague.    Pp.  12.     Price,  5  cents. 
Hul.   98,  The  Effect  of  Severe  and  Prolonged  Muscular  Work  on  Food  Consumption,  Digestion,  and 

Metabolism,  hy  W.  O.  At  water  and  II   C.  Sherman,  and  the  Mechanical  Work  and  Efficiency 

of  Bicyclers,  by  R.  C.  Carpenter.    Pp.  67     Price.  5  cents. 
Bui.  101.  studies  on  Bread  and  Bread  Making  at  the  University  of  Minnesota  in  1899  and  1300.    By 

Harry  Snyder.     Pp.  66.     Price,  5  cents. 
Bid.  102.  Experiments  on  Losses  In  Cooking  Meat,  1898-1900.    By  H.  S.  Grihdley,  with  the  coopera- 
tion of  H.  McCormack  and  H.  C.  Porter.     Pp.  64.     Price.  6  cent-. 
Bui.  H>7.  Nutrition   Investigations  Among   Fruitarians  and  Chinese  at   the  California   Agricultural 

Experiment  Station.  1899-1991.     By  M.  K.  Jaffa.     Pp.  43.     Price.  5  cents. 
Bnl.  loo.  Experiments  on  the  Metabolism  of  Matter  and  Energy  in  the  Human  Body.  1*98-1900.    By 

W.  O.  Atwater  and  F.  G.  Benedict,  with  the  cooperation  of  A.  P.  Bryant,  A.  W.  Smith,  and 

J.  F.  Snell.    Pp.  147.    Price,  10  cents. 
Bui.  lit-..  Dietary  Studies  in  New  York  City  in   1X%  and  1S;»7.     Hy  W.  0.  Atwater  and  A.  P.   Bryant. 

Pp.  83.     Price,  •">  cents. 
Bui.  117.  Experiments  on  the  Effect  of  Muscular  Work  upon  the  Digestibility  of  Food  and  the  Metab- 
olism of  Nitrogen.    Conducted  at  the  University  of  Tennessee,  1899-1900.     By  C.  E.  Wait. 

Pp.  43.    Price,  5  cents. 
Bui.  121.  Experiments  on  the   Metabolism  of  Nitrogen,  Sulphur,  and  Phosphorus  in   the   Human 
Organism.    By  H.  C.  Sherman.    Pp.  47. 

FARMERS'    BULLETINS. 

*Bul.  23.  Foods:  Nutritive  Value  and  Cost.     By  W.  Q.  Atwater.     Pp.  32. 

Bui.    34.  Meats:  Composition  and  Cooking.     By  C.  D.  Woods.     Pp.  29. 

Bui.    74.  Milk  as  Food.     Pp.  39. 

Bui.    86.  Fish  as  Food.     By  C.  F-.  Lang-worthy.     Pp.30. 

Bui.    93.  Sugar  as  Food.     By  Mary  H.  Abel.     Pp.  27. 

Bui.  112.  Bread  and  the  Principles  of  Bread  Making.     By  Helen  W.  Atwater.     Pp.  39. 

Bui.  121.  Beans,  Peas;  and  other  Legumes  as  Food.     By  Mary  H.  Abel.     Pp  32. 

Bui.  128.  Eggs  and  their  Uses  as  Food.     Hy  C.  F.  Langworthy.     Pp.  32. 

Bui.  142.  Principles  of  Nutrition  and  Nutritive  Value  of  Food.     By  W.  O.  Atwater.     Pp.  48. 

CIRClLAR. 

(  ir.     16.  The  Functions  and  Uses  of  Food.    By  C.  F.  Langworthy.     Pp.  10. 

SEPARATES. 

*Food  and  Diet.     By  W.  O.  Atwater.     Reprinted  from  Yearbook  of  Department  of  Agriculture  for 

1894.     Pp.  44. 
Some  Results  of  Dietary  Studies  in  the  United  States.     By  A.  P.  Bryant.     Reprinted  from  Yearbook 

of  Department  of  Agriculture  for  1898.     Pp.  14. 
Development  of  the  Nutrition  Investigations  of  ihe  Department  of  Agriculture.     By  A.  C.  True  and 

R.  D.  Milner.     Reprinted  from  Yearbook  of  Department  of  Agriculture  for  1899.     Pp.  16. 
The  Value  of  Potatoes  as  Food.     By  C.  F.  Langworthy.     Reprinted  from  Yearbook  of  Department  of 

Agriculture  for  1900.     Pp.  16.  1 

Dietaries  in  Public  Institutions.     By  W.  0.  Atwater.     Reprinted  from  Yearbook  of  Department  of 

Agriculture  for  189L     Pp.  18. 
Scope  and  Results  of  the  Nutrition  Investigations  of  the  Office  of  Experiment  Stations.     Reprinted 

from  Annual  Report  of  the  Office  of  Experiment  Stations  for  the  year  ended  June  30,  1901. 

Pp.  50. 


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